As Russia’s airstrikes grow more successful, NATO countries weigh shooting down missiles over Ukraine.

A debate between NATO allies about whether to take a more aggressive role in protecting Ukraine’s skies, including by directly shooting down Russian missiles and drones, has picked up steam in recent weeks.

“Whether it’s done by NATO or NATO countries … that’s one of the issues we want to have a discussion on,” one European official said. A senior NATO official told Semafor that “a lot of these discussions” are not taking place collectively at the NATO level but rather between individual member states.

The conversation has been ongoing inside the alliance for some time but “took on a little bit more realism” after the US and allies shot down Iranian drones bound for Israel back in April, said Kurt Volker, a former US ambassador to NATO.

But the proposal has significant roadblocks and is a divisive idea within the alliance. Poland and Romania are “very interested” in the idea, Volker said, but he noted that the US and Germany have been resistant to it due to the risk of drawing NATO directly into a conflict with Russia.

When asked about the possibility of NATO air defenses shooting down missiles over Ukraine at a meeting of the NATO Parliamentary Assembly this week, Secretary General Jens Stoltenberg replied that “the more you are supportive of Ukraine, the more cautious we should be to ask for things that can divide us.”

“I’m not holding my breath right now with regard to actively providing air defense for Ukraine from NATO countries,” a second European official said, citing Washington’s opposition to Western countries getting directly involved in military operations. “European nations will look to the US for leadership, and I feel that we are not yet in a place where the US would seriously reconsider the whole strategy around Ukraine.”

Poland, which borders western Ukraine, has repeatedly signaled that such a policy is under consideration. Polish Deputy Foreign Minister Andrzej Shejnahas has said that NATO is analyzing whether “missiles should be shot down when they are very close to the NATO border.”

“For the time being, no decisions have been made in this matter,” a spokesperson for the Polish Ministry of National Defense told Semafor, noting that “the possible coverage of part of Ukraine’s territory by allied air defense is an extremely complex issue.”