Anti-government demonstrators occupying a historic field in the Thai capital on Sunday installed a plaque symbolizing the country's transition to democracy to replace the original one that was mysteriously ripped and stolen three years ago, as they vowed to press on with calls for new elections and reform of the monarchy.

The mass student-led rally that began Saturday is the largest in a series of protests this year, with thousands camping overnight at Sanam Luang field near the royal palace. On Sunday, they began marching to an undisclosed location, saying they want to hand over a petition to the king's adviser.

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Pro-democracy student leaders hold a plaque declaring "This country belongs to the people" at the Sanam Luang field during a protest in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoSakchai Lalit)

Anti-government demonstrators occupying a historic field in the Thai capital on Sunday installed a plaque symbolizing the country's transition to democracy to replace the original one that was mysteriously ripped and stolen three years ago, as they vowed to press on with calls for new elections and reform of the monarchy.

Pro-democracy protesters raise a three-fingers, symbol of resistance salute during a rally at Sanam Luang in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators who occupied a historic field in Thailand's capital overnight continued with their rally on Sunday to support the demands of a student-led protest movement for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

“At the dawn of Sept. 20, here is where the people proclaim that this country belongs to the people,” read part of the inscription on the plaque. In April 2017, the original plaque vanished from Bangkok’s Royal Plaza and was replaced by one praising the monarchy.

Pro-democracy protesters gather at the Sanam Luang field during a protest in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoWason Wanichakorn)

Still, such calls took the nation by surprise. Protesters' demands seek to limit the king’s powers, establish tighter controls on palace finances and allow open discussion of the monarchy. Their boldness was unprecedented, as the monarchy is considered sacrosanct in Thailand with a harsh law that mandates a three- to 15-year prison term for defaming it.

Pro-democracy student leaders raise a three-fingers salute, a symbol of resistance during a protest in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoSakchai Lalit)

The crowd were a disparate batch. They included an LGBTQ contingent waving iconic rainbow banners while red flags sprouted across the area, representing Thailand’s Red Shirt political movement, which battled the country’s military in Bangkok’s streets 10 years ago.

Pro-democracy protesters raise a three-fingers, symbol of resistance salute as others observe Buddhist religious rituals during a rally at Sanam Luang in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators who occupied a historic field in Thailand's capital overnight continued with their rally on Sunday to support the demands of a student-led protest movement for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

Their core demands were the dissolution of parliament with fresh elections, a new constitution and an end to intimidation of political activists.

A pro-democracy protester raises a three-fingers, symbol of resistance salute during a rally at Sanam Luang in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators who occupied a historic field in Thailand's capital overnight continued with their rally on Sunday to support the demands of a student-led protest movement for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

“This is why they look and act differently and why they are so confounding for the regime,” he said. “What the regime and its supporters see is relatively well-off kids turned against them and this confounds them.”

Pro-democracy student leaders hold a plaque declaring "This country belongs to the people" at the Sanam Luang field during a protest in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoSakchai Lalit)

“If we had a good government, a democratic government, our politics, our education and our health care system would be better than this," said protester Amorn Panurang. "This is our dream. And we hope that our dream would come true.”

Pro-democracy protesters gather at the Sanam Luang field during a protest in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoWason Wanichakorn)

Pro-democracy protesters gather at the Sanam Luang field during a protest in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoWason Wanichakorn)

Pro-democracy protesters are seen during dawn at the Sanam Luang field during a protest in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoSakchai Lalit)

Pro-democracy protesters are seen during dawn at the Sanam Luang field during a protest in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoSakchai Lalit)

A pro-democracy protester raises a three-fingers, symbol of resistance salute during a rally at Sanam Luang in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators who occupied a historic field in Thailand's capital overnight continued with their rally on Sunday to support the demands of a student-led protest movement for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

A pro-democracy protester raises a three-fingers, symbol of resistance salute during a rally at Sanam Luang in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators who occupied a historic field in Thailand's capital overnight continued with their rally on Sunday to support the demands of a student-led protest movement for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

Pro-democracy protesters practice Buddhist religious rituals during a rally at Sanam Luang in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators who occupied a historic field in Thailand's capital overnight continued with their rally on Sunday to support the demands of a student-led protest movement for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

Pro-democracy protesters practice Buddhist religious rituals during a rally at Sanam Luang in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators who occupied a historic field in Thailand's capital overnight continued with their rally on Sunday to support the demands of a student-led protest movement for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

Pro-democracy protesters raise a three-fingers, symbol of resistance salute during a rally at Sanam Luang in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators who occupied a historic field in Thailand's capital overnight continued with their rally on Sunday to support the demands of a student-led protest movement for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

Pro-democracy protesters raise a three-fingers, symbol of resistance salute during a rally at Sanam Luang in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators who occupied a historic field in Thailand's capital overnight continued with their rally on Sunday to support the demands of a student-led protest movement for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

Pro-democracy student leaders install a plaque declaring "This country belongs to the people" at the Sanam Luang field during a protest in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoSakchai Lalit)

Pro-democracy student leaders install a plaque declaring "This country belongs to the people" at the Sanam Luang field during a protest in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoSakchai Lalit)

A pro-democracy protester raises a three-fingers, symbol of resistance salute during a rally at Sanam Luang in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators who occupied a historic field in Thailand's capital overnight continued with their rally on Sunday to support the demands of a student-led protest movement for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

A pro-democracy protester raises a three-fingers, symbol of resistance salute during a rally at Sanam Luang in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators who occupied a historic field in Thailand's capital overnight continued with their rally on Sunday to support the demands of a student-led protest movement for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

Pro-democracy protesters display the national flag at the Sanam Luang field during a protest in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoSakchai Lalit)

Pro-democracy protesters display the national flag at the Sanam Luang field during a protest in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoSakchai Lalit)

A pro-democracy protester sleeps in Sanam Luang, a historic field protesters occupied for an over-night protest rally in Bangkok, Thailand, early Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

A pro-democracy protester sleeps in Sanam Luang, a historic field protesters occupied for an over-night protest rally in Bangkok, Thailand, early Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

Pro-democracy protesters who occupied Sanam Luang, a historic field for an over-night protest rally, cook a meal in Bangkok, Thailand, early Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

Pro-democracy protesters who occupied Sanam Luang, a historic field for an over-night protest rally, cook a meal in Bangkok, Thailand, early Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

Pro-democracy protesters who occupied Sanam Luang, a historic field for an over-night protest rally, cook a meal in Bangkok, Thailand, early Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

Pro-democracy protesters who occupied Sanam Luang, a historic field for an over-night protest rally, cook a meal in Bangkok, Thailand, early Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

A Buddhist monk walks distributing face masks to pro-democracy protesters who occupied Sanam Luang, a historic field for an over-night protest rally at dawn in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

A Buddhist monk walks distributing face masks to pro-democracy protesters who occupied Sanam Luang, a historic field for an over-night protest rally at dawn in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

A Buddhist monk walks distributing face masks to pro-democracy protesters who occupied Sanam Luang, a historic field for an over-night protest rally at dawn in Bangkok, Thailand, early Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

A Buddhist monk walks distributing face masks to pro-democracy protesters who occupied Sanam Luang, a historic field for an over-night protest rally at dawn in Bangkok, Thailand, early Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

Pro-democracy protesters sleep in Sanam Luang, a historic field protesters occupied for an over-night protest rally in Bangkok, Thailand, early Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

Pro-democracy protesters sleep in Sanam Luang, a historic field protesters occupied for an over-night protest rally in Bangkok, Thailand, early Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

Pro-democracy protesters hold up mobile phone lights to live music during a rally at Sanam Luang in Bangkok, Thailand, Saturday, Sept. 19, 2020. Protesters gathered Saturday in Bangkok for the most ambitious rally so far in a pro-democracy campaign that has shaken up the government and the country's conservative establishment. (AP PhotoGemunu Amarasinghe)

Pro-democracy protesters hold up mobile phone lights to live music during a rally at Sanam Luang in Bangkok, Thailand, Saturday, Sept. 19, 2020. Protesters gathered Saturday in Bangkok for the most ambitious rally so far in a pro-democracy campaign that has shaken up the government and the country's conservative establishment. (AP PhotoGemunu Amarasinghe)

A group of activists drilled a hole in front of a makeshift stage in Sanam Luang and laid down a round brass plaque, commemorating a 1932 revolution that changed Thailand from an absolute monarchy to a constitutional monarchy.

Pro-democracy student leaders hold a plaque declaring "This country belongs to the people" at the Sanam Luang field during a protest in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoSakchai Lalit)

Pro-democracy student leaders hold a plaque declaring "This country belongs to the people" at the Sanam Luang field during a protest in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoSakchai Lalit)

“At the dawn of Sept. 20, here is where the people proclaim that this country belongs to the people,” read part of the inscription on the plaque. In April 2017, the original plaque vanished from Bangkok’s Royal Plaza and was replaced by one praising the monarchy.

“The nation does not belong to only one person, but belongs to us all. Therefore, I would like to ask holy spirits to stay with us and bless the people’s victory,” student leader Parit “Penguin” Chirawak told the crowd.

Another activist, Panusaya Sithijirawattanakul, said their demands do not propose getting rid of the monarchy. “They are proposals with good intentions to make the institution of the monarchy remain graciously above the people under democratic rule.”

Pro-democracy protesters raise a three-fingers, symbol of resistance salute during a rally at Sanam Luang in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators who occupied a historic field in Thailand's capital overnight continued with their rally on Sunday to support the demands of a student-led protest movement for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

Pro-democracy protesters raise a three-fingers, symbol of resistance salute during a rally at Sanam Luang in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators who occupied a historic field in Thailand's capital overnight continued with their rally on Sunday to support the demands of a student-led protest movement for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

Still, such calls took the nation by surprise. Protesters' demands seek to limit the king’s powers, establish tighter controls on palace finances and allow open discussion of the monarchy. Their boldness was unprecedented, as the monarchy is considered sacrosanct in Thailand with a harsh law that mandates a three- to 15-year prison term for defaming it.

Organizers had predicted that as many as 50,000 people would take part in the weekend’s protest, but Associated Press reporters estimated that around 20,000 people were present by Saturday evening.

“By holding their protest on Sanam Luang — a long-time site of recreation and protest for the people, taken over in recent years by the monarchy — the protestors have won a significant victory,” said Tyrell Haberkorn, a Thai studies scholar at the University of Wisconsin-Madison. “Their resounding message is that Sanam Luang, and the country, belong to the people.”

Pro-democracy protesters gather at the Sanam Luang field during a protest in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoWason Wanichakorn)

Pro-democracy protesters gather at the Sanam Luang field during a protest in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoWason Wanichakorn)

The crowd were a disparate batch. They included an LGBTQ contingent waving iconic rainbow banners while red flags sprouted across the area, representing Thailand’s Red Shirt political movement, which battled the country’s military in Bangkok’s streets 10 years ago.

There were skits and music, and speakers gave fiery speeches late Saturday accusing the government of incompetence, corruption in the military and failing to protect women’s rights. At least 8,000 police officers were reportedly deployed for the event.

“The people who came here today came here peacefully and are really calling for democracy,” said Panupong Jadnok, one of the protest leaders.

Pro-democracy student leaders raise a three-fingers salute, a symbol of resistance during a protest in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoSakchai Lalit)

Pro-democracy student leaders raise a three-fingers salute, a symbol of resistance during a protest in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoSakchai Lalit)

Their core demands were the dissolution of parliament with fresh elections, a new constitution and an end to intimidation of political activists.

They believe that Prime Minister Prayuth Chan-ocha, who as army commander led a 2014 coup toppling an elected government, was returned to power unfairly in last year’s general election because the laws had been changed to favor a pro-military party. Protesters say a constitution promulgated under military rule is undemocratic.

The students are too young to have been caught up in the sometimes violent partisan battles that roiled Thailand a decade ago, said Kevin Hewison, a University of North Carolina professor emeritus and a veteran Thai studies scholar.

Pro-democracy protesters raise a three-fingers, symbol of resistance salute as others observe Buddhist religious rituals during a rally at Sanam Luang in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators who occupied a historic field in Thailand's capital overnight continued with their rally on Sunday to support the demands of a student-led protest movement for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

Pro-democracy protesters raise a three-fingers, symbol of resistance salute as others observe Buddhist religious rituals during a rally at Sanam Luang in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators who occupied a historic field in Thailand's capital overnight continued with their rally on Sunday to support the demands of a student-led protest movement for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

“This is why they look and act differently and why they are so confounding for the regime,” he said. “What the regime and its supporters see is relatively well-off kids turned against them and this confounds them.”

The appearance of the Red Shirts, while boosting the protest numbers, links the new movement to mostly poor rural Thais, supporters of former populist billionaire Prime Minister Thaksin Shinawatra who was ousted in a 2006 coup. Thaksin was opposed by the country’s traditional royalist establishment.

The sometimes violent struggle between Thaksin’s supporters and the conservative foes left Thai society polarized. Thaksin, who now lives in exile, noted on Twitter on Saturday that it was the anniversary of his fall from power and posed the rhetorical question of how the nation had fared since then.

A pro-democracy protester raises a three-fingers, symbol of resistance salute during a rally at Sanam Luang in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators who occupied a historic field in Thailand's capital overnight continued with their rally on Sunday to support the demands of a student-led protest movement for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

A pro-democracy protester raises a three-fingers, symbol of resistance salute during a rally at Sanam Luang in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators who occupied a historic field in Thailand's capital overnight continued with their rally on Sunday to support the demands of a student-led protest movement for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

“If we had a good government, a democratic government, our politics, our education and our health care system would be better than this," said protester Amorn Panurang. "This is our dream. And we hope that our dream would come true.”

Arrests for earlier actions on charges including sedition have failed to faze the young activists. They had been denied permission to enter the Thammasat University campus and Sanam Luang on Saturday, but when they pushed, the authorities retreated, even though police warned them that they were breaking the law.

Pro-democracy student leaders hold a plaque declaring "This country belongs to the people" at the Sanam Luang field during a protest in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoSakchai Lalit)

Pro-democracy student leaders hold a plaque declaring "This country belongs to the people" at the Sanam Luang field during a protest in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoSakchai Lalit)

Pro-democracy protesters gather at the Sanam Luang field during a protest in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoWason Wanichakorn)

Pro-democracy protesters gather at the Sanam Luang field during a protest in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoWason Wanichakorn)

Pro-democracy protesters are seen during dawn at the Sanam Luang field during a protest in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoSakchai Lalit)

Pro-democracy protesters are seen during dawn at the Sanam Luang field during a protest in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoSakchai Lalit)

A pro-democracy protester raises a three-fingers, symbol of resistance salute during a rally at Sanam Luang in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators who occupied a historic field in Thailand's capital overnight continued with their rally on Sunday to support the demands of a student-led protest movement for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

A pro-democracy protester raises a three-fingers, symbol of resistance salute during a rally at Sanam Luang in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators who occupied a historic field in Thailand's capital overnight continued with their rally on Sunday to support the demands of a student-led protest movement for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

Pro-democracy protesters practice Buddhist religious rituals during a rally at Sanam Luang in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators who occupied a historic field in Thailand's capital overnight continued with their rally on Sunday to support the demands of a student-led protest movement for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

Pro-democracy protesters practice Buddhist religious rituals during a rally at Sanam Luang in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators who occupied a historic field in Thailand's capital overnight continued with their rally on Sunday to support the demands of a student-led protest movement for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

Pro-democracy protesters raise a three-fingers, symbol of resistance salute during a rally at Sanam Luang in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators who occupied a historic field in Thailand's capital overnight continued with their rally on Sunday to support the demands of a student-led protest movement for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

Pro-democracy protesters raise a three-fingers, symbol of resistance salute during a rally at Sanam Luang in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators who occupied a historic field in Thailand's capital overnight continued with their rally on Sunday to support the demands of a student-led protest movement for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

Pro-democracy student leaders install a plaque declaring "This country belongs to the people" at the Sanam Luang field during a protest in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoSakchai Lalit)

Pro-democracy student leaders install a plaque declaring "This country belongs to the people" at the Sanam Luang field during a protest in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoSakchai Lalit)

A pro-democracy protester raises a three-fingers, symbol of resistance salute during a rally at Sanam Luang in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators who occupied a historic field in Thailand's capital overnight continued with their rally on Sunday to support the demands of a student-led protest movement for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

A pro-democracy protester raises a three-fingers, symbol of resistance salute during a rally at Sanam Luang in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators who occupied a historic field in Thailand's capital overnight continued with their rally on Sunday to support the demands of a student-led protest movement for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

Pro-democracy protesters display the national flag at the Sanam Luang field during a protest in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoSakchai Lalit)

Pro-democracy protesters display the national flag at the Sanam Luang field during a protest in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoSakchai Lalit)

A pro-democracy protester sleeps in Sanam Luang, a historic field protesters occupied for an over-night protest rally in Bangkok, Thailand, early Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

A pro-democracy protester sleeps in Sanam Luang, a historic field protesters occupied for an over-night protest rally in Bangkok, Thailand, early Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

Pro-democracy protesters who occupied Sanam Luang, a historic field for an over-night protest rally, cook a meal in Bangkok, Thailand, early Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

Pro-democracy protesters who occupied Sanam Luang, a historic field for an over-night protest rally, cook a meal in Bangkok, Thailand, early Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

Pro-democracy protesters who occupied Sanam Luang, a historic field for an over-night protest rally, cook a meal in Bangkok, Thailand, early Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

Pro-democracy protesters who occupied Sanam Luang, a historic field for an over-night protest rally, cook a meal in Bangkok, Thailand, early Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

A Buddhist monk walks distributing face masks to pro-democracy protesters who occupied Sanam Luang, a historic field for an over-night protest rally at dawn in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

A Buddhist monk walks distributing face masks to pro-democracy protesters who occupied Sanam Luang, a historic field for an over-night protest rally at dawn in Bangkok, Thailand, Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

A Buddhist monk walks distributing face masks to pro-democracy protesters who occupied Sanam Luang, a historic field for an over-night protest rally at dawn in Bangkok, Thailand, early Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

A Buddhist monk walks distributing face masks to pro-democracy protesters who occupied Sanam Luang, a historic field for an over-night protest rally at dawn in Bangkok, Thailand, early Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

Pro-democracy protesters sleep in Sanam Luang, a historic field protesters occupied for an over-night protest rally in Bangkok, Thailand, early Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

Pro-democracy protesters sleep in Sanam Luang, a historic field protesters occupied for an over-night protest rally in Bangkok, Thailand, early Sunday, Sept. 20, 2020. Thousands of demonstrators turned out Saturday for a rally to support the student-led protest movement's demands for new elections and reform of the monarchy. (AP PhotoGemunu Amarasinghe)

Pro-democracy protesters hold up mobile phone lights to live music during a rally at Sanam Luang in Bangkok, Thailand, Saturday, Sept. 19, 2020. Protesters gathered Saturday in Bangkok for the most ambitious rally so far in a pro-democracy campaign that has shaken up the government and the country's conservative establishment. (AP PhotoGemunu Amarasinghe)

Pro-democracy protesters hold up mobile phone lights to live music during a rally at Sanam Luang in Bangkok, Thailand, Saturday, Sept. 19, 2020. Protesters gathered Saturday in Bangkok for the most ambitious rally so far in a pro-democracy campaign that has shaken up the government and the country's conservative establishment. (AP PhotoGemunu Amarasinghe)