North Korea threatened Thursday to resume insults of U.S. President Donald Trump and consider him a “dotard” if he keeps using words that provoke the North.

Choe Son Hui, the first vice foreign minister, issued the warning days after Trump spoke of a possible military option toward the North and revived his “rocket man” nickname for North Korean leader Kim Jong Un.

The development comes as prospects dim for a resumption of nuclear diplomacy between the two countries. In recent weeks, North Korea has hinted at lifting its moratorium on nuclear and long-range missile tests if the Trump administration fails to make substantial concessions in nuclear diplomacy before the year’s end.

Choe said Trump’s remarks “prompted the waves of hatred of our people against the U.S.” because as they showed “no courtesy when referring to the supreme leadership of dignity” of North Korea.

She said North Korea will respond with its own harsh language if Trump again uses similar phrases and shows that he is intentionally provoking North Korea.

“If any language and expressions stoking the atmosphere of confrontation are used once again on purpose at a crucial moment as now, that must really be diagnosed as the relapse of the dotage of a dotard,” Choe said.

During a visit to London, Trump on Tuesday said his relationship with Kim was “really good” but also called for him to follow up on a commitment to denuclearize. Trump added, “We have the most powerful military we ever had, and we are by far the most powerful country in the world and hopefully we don’t have to use it. But if we do, we will use it.”

Trump also said Kim “likes sending rockets up, doesn’t he?” He added that “That’s why I call him rocket man.”

In 2017, Trump and Kim traded threats of destruction as North Korea carried out a slew of high-profile weapons tests aimed at acquiring an ability to launch nuclear strikes on the U.S. mainland. Trump said he would bring “fire and fury” on North Korea and derided Kim as “little rocket man,” while Kim threatened to turn Washington into “a sea of fire” and called Trump a “mentally deranged U.S. dotard.”

The two leaders have avoided such words and developed better relations after North Korea entered nuclear negotiations with the U.S. last year. Trump even said he and Kim “fell in love.”