France, Germany and Spain agreed Monday to develop a European fighter jet and air combat system, as they bolster efforts to reduce their dependency on the United States.

Defense ministers from the three countries signed an agreement at the Paris Air Show that lays out how the countries will cooperate on the project, which would include a new-generation combat aircraft.

French President Emmanuel Macron presided over the signing. The project fits in with his ambition to increase European cooperation at a time when the United States under President Donald Trump is showing an increasing reluctance to support the continent militarily.

Airbus Defence and Space Chief Executive Officer Dirk Hoke, left, Dassault Aviation Chairman and CEO Eric Trappier, second left, German Defense Minister Ursula von der Leyen, third left, French President Emmanuel Macron, Spanish Defense Minister Margarita Robles, second right, and French Defense Minister Florence Parly attend the unveiling of the French-German-Spanish new generation fighter model during a visit the Paris Air Show in Le Bourget Airport near Paris, France, Monday June 17, 2019. (Yoan ValatPool via AP)

Airbus Defence and Space Chief Executive Officer Dirk Hoke, left, Dassault Aviation Chairman and CEO Eric Trappier, second left, German Defense Minister Ursula von der Leyen, third left, French President Emmanuel Macron, Spanish Defense Minister Margarita Robles, second right, and French Defense Minister Florence Parly attend the unveiling of the French-German-Spanish new generation fighter model during a visit the Paris Air Show in Le Bourget Airport near Paris, France, Monday June 17, 2019. (Yoan ValatPool via AP)

It's going to take time though. The Future Combat Air System (FCAS) is not expected to be operational until 2040. Requirements for the air combat system that will also include drones will be decided by 2027 and the development phase should start by 2030.

French Defense minister Florence Parly said the deal is "concrete proof that Europe is capable of anticipating tomorrow's great strategic challenges."

"The FCAS is a major asset to tackle the power struggles of the second half of the 21st century. What is happening today is historic," she said.

French President Emmanuel Macron, Eric Trappier, Chairman and CEO of Dassault Aviation, Dirk Hoke, CEO of Airbus Defense and Space, Spanish Defense Minister Margarita Robles, German Defense Minister Ursula von der Leyen and French Defense Minister Florence Parly attend the unveiling of the French-German-Spanish New Generation Fighter (NGF) model during a visit at Le Bourget Airport near Paris, France, Monday June 17, 2019. The world's aviation elite are gathering at the Paris Air Show with safety concerns on many minds after two crashes of the popular Boeing 737 Max. (Benoit TessierPool via AP)

French President Emmanuel Macron, Eric Trappier, Chairman and CEO of Dassault Aviation, Dirk Hoke, CEO of Airbus Defense and Space, Spanish Defense Minister Margarita Robles, German Defense Minister Ursula von der Leyen and French Defense Minister Florence Parly attend the unveiling of the French-German-Spanish New Generation Fighter (NGF) model during a visit at Le Bourget Airport near Paris, France, Monday June 17, 2019. The world's aviation elite are gathering at the Paris Air Show with safety concerns on many minds after two crashes of the popular Boeing 737 Max. (Benoit TessierPool via AP)

Dassault Aviation and Airbus are set to build the jets which will eventually replace Rafale and Eurofighters.

The program was launched by Macron and German Chancellor Angela Merkel in 2017. Airbus says it will be connected and operable with a wide variety of aircraft, satellites, NATO systems as well as land and naval combat systems.

Authorities have not said how much it would cost but the dpa news agency estimates it could be 100 billion euros ($112 billion).

German Defense Minister Ursula von der Leyen, left, Spanish Defence Minister Margarita Robles, second left, French President Emmanuel Macron and Dassault Aviation Chairman and CEO Eric Trappier, right, visit the Paris Air Show in Le Bourget Airport near Paris, France, Monday June 17, 2019. (Yoan ValatPool via AP)

German Defense Minister Ursula von der Leyen, left, Spanish Defence Minister Margarita Robles, second left, French President Emmanuel Macron and Dassault Aviation Chairman and CEO Eric Trappier, right, visit the Paris Air Show in Le Bourget Airport near Paris, France, Monday June 17, 2019. (Yoan ValatPool via AP)

French President Emmanuel Macron, German Defense Minister Ursula von der Leyen, left, French Defense Minister Florence Parly, second left, and Spanish Defense Minister Margarita Robles, right, watch Airbus Defense and Space Chief Executive Officer Dirk Hoke (down right) and Dassault Aviation Chairman and CEO Eric Trappier during a signature ceremony as part as the unveiling of the French-German-Spanish new generation fighter model during Le Bourget Airport near Paris, France, Monday June 17, 2019. (Yoan ValatPool via AP)

French President Emmanuel Macron, German Defense Minister Ursula von der Leyen, left, French Defense Minister Florence Parly, second left, and Spanish Defense Minister Margarita Robles, right, watch Airbus Defense and Space Chief Executive Officer Dirk Hoke (down right) and Dassault Aviation Chairman and CEO Eric Trappier during a signature ceremony as part as the unveiling of the French-German-Spanish new generation fighter model during Le Bourget Airport near Paris, France, Monday June 17, 2019. (Yoan ValatPool via AP)