COLOGNE, Germany — The European Union is considering setting up its own air defense shield after bloc leaders threw their support behind a Greek-Polish initiative to that effect this week.

The two countries’ prime minsters, Kyriakos Mitsotakis and Donald Tusk, respectively, pitched the idea to European Commission President Ursula von der Leyen in a letter earlier this month.

After von der Leyen, who is eyeing a second term following elections in early June, swiftly endorsed the idea, the EU’s top diplomat, Josep Borrell, also signaled support.

“I welcome that member states say that to defend our airspace, why should we look at that in a fragmented manner?” Borrell said ahead of a May 28 meeting of the Foreign Affairs Council in Brussels.

Borrell told reporters the idea raises plenty of questions. “But the devil is in the details,” he said. “Where will these air defenses be put? At the border? Which border? With which capacities? With which funding?”

In their letter, Mitsotakis and Tusk said they envision “a comprehensive air defense system to protect our common EU airspace against all the incoming threats,” citing Russia’s war against Ukraine as key motivation.

Besides the tangible, military benefits such an endeavor could bring, the two leaders argued that a joint “flagship” program would signal to would-be attackers that the EU is united on defense.

That wording could be seen as a veiled dig at Berlin, where officials are well underway in assembling an air defense coalition under their European Sky Shield Initiative, which now counts 21 member countries. German officials created the initiative in 2022 amid the shock over Russian troops targeting Ukrainian infrastructure and population centers with missiles and drones.

Poland’s Tusk previously said he wants his country to join, but he has faced opposition from the president, Andrzej Duda, who was reelected in 2020 with backing of the then-ruling Law and Justice party.

The project is essentially a European outgrowth of NATO’s air defense architecture, aimed at coordinating national procurements and ensuring interoperability between sensors and interceptors.

But not all EU member states have bought into the idea, partly because the aperture for sourcing the requisite hardware leans heavily on non-European products, including the Israeli-American Arrow 3 missile and the U.S. Patriot system.

The German reaction to the Greek-Polish proposal has been muted, with officials saying they have nothing against it as long it doesn’t interfere with their initiative.

“NATO remains the biggest and most important defense alliance for Europe,” State Secretary Siemtje Möller told reporters ahead of the Foreign Affairs Council meeting this week. She floated the idea of using the bloc’s procurement and funding channels as a feeder mechanism for Germany’s initative.

In the end, the council meeting came and went without any action on the issue, according to officials in Berlin and Brussels. A spokesperson with the German government said the Greek-Polish proposal came up only on the periphery, while an EU spokesperson said formalizing national proposals wasn’t the panel’s job to begin with.