U.S. President Donald Trump responded furiously to French President Emmanuel Macron’s idea to build up Europe’s joint forces. The billionaire tweeted his anger after arriving in Paris on Saturday to commemorate the end of World War I.

“President Macron of France has just suggested that Europe build its own military in order to protect itself from the U.S., China, and Russia. Very insulting, but perhaps Europe should first pay its fair share of NATO, which the U.S. subsidizes greatly!” Trump tweeted.

Trump has repeatedly slammed the NATO members for not increasing their military budget. Based on the pact data as of July 2018, Washington’s contribution will account for 70 percent of the NATO budget this year.

Initially, NATO Secretary General Jens Stoltenberg instructed the organization’s 29 members to up their defense budget to two percent of their GDP, which was opposed by Trump, who wanted them to use four percent of their GDP for military spending.

Previously, in an interview with Europe 1 Radio, Macron called for the establishment of the true European army to tackle threats from China, Russia and even the U.S. Macron added that Europe must start reducing its dependence on Washington after Trump announced the U.S. would leave the nuclear agreement that was signed in the Cold War era.

“We have to protect ourselves with respect to China, Russia and even the United States of America,” Macron said.

The deal, known as the Intermediate-Range Nuclear Forces Treaty (INF), was signed on December 8, 1987, by the former U.S. President Ronald Reagan and former Russian (formerly known as the Soviet Union) leader Mikhail Gorbachev.

There are Some Pros and Cons Regarding the EU Army

In Brussels, the idea of the creation of the European Union (EU) army has gained support from those who believe that the continent’s defense and foreign policy cooperation has been left behind compared to their economic policy.

After the Crimea annexation by Russia, the European Commission President Jean-Clause Juncker said in March 2015 that the 28-nation bloc needed its military strength to be considered seriously in international affairs. He also suggested that the decision regarding foreign policy must be taken by the majority of the votes.

A European Army is Unlikely

Each European country is different in defense culture and its background. A Dutch-German cooperation was driven by economic reasons, as Holland no longer used its old equipment, and decided to have a joint-training with Germany. Nordic defense co-operation (NORDEFCO) has involved Finnish and Scandinavian forces in joint training for a long time.

Despite being one of the world’s most prosperous countries, Germany is still struggling to increase its defense budget to two percent of its GDP. Last February, France announced that it would up its defense budget by 40 percent and would hit 50 billion Euros by 2025, bringing it to two percent of its GDP.

The creation of an EU army would overlap with NATO as well. There is a wide ideological difference between the Gaullists who want Europe to be independent of the U.S. influence and the Atlanticists who want to maintain the existence of NATO and prefer Washington’s involvement, especially former communist states who still consider Russia as a threat.

EU Head of Foreign Policy Federica Mogherini said in 2017 that the idea of the European army will likely come true in the next 50, 60 or 100 years.