German Chancellor Angela Merkel joined French President Emmanuel Macron in calling for a European army Tuesday, stressing that such a military would be a complement to NATO, not stand in opposition to it.

Merkel, who will not be seeking reelection, has expressed such sentiment before, says the New York Times. Tuesday’s speech was notable, however, in that it came just hours after aggressive comments by U.S. President Donald Trump, who launched a tirade against France via Twitter Tuesday morning. Trump’s comments were seemingly spurred by Macron’s suggestion of a European army in an interview last week.

In her speech to the European Parliament, Merkel promoted the idea of more sovereign security to compliment NATO, an alliance Trump has thrown into question since taking the presidency. Last summer, he reportedly threatened to pull the U.S. out if other member states don’t spend more on defense.

“The days where we can unconditionally rely on others are gone,” Merkel said Tuesday. “That means that we Europeans should take our fate more into our own hands if we want to survive as a European community.”

“We should work on a vision to create a real European army one day,” she added.

Merkel also suggested the creation of a European Security Council with rotating seats for member states, allowing for quicker decisions on foreign policy.

The European Union has taken steps toward military cooperation in the past: last year, 23 of the 28 member states signed on to the Pesco program, which aims to create more efficiency across the European militaries. The program also created joint investments in military equipment, research, and development.

If the EU decides to move toward a united army in conjunction with NATO, it’s uncertain how such an army would be organized or financed—especially considering many countries don’t spend the 2% of GDP on defense presently suggested by NATO. It’s a long-term goal, but one Merkel said will show the world “that there will never again be war between European nations.”