“If they can buy it in Europe, fantastic — priority one,” he said. “Ukraine defense industry base, great. But we all know that without this flow of weaponry from the U.S., we cannot keep Ukraine in the fight. Literally not. They now provide essential interceptors, for example, to take down as many missiles as possible going into Kyiv, Kharkiv and other cities, night by night.”

There is also pressure from the Netherlands and other countries to ensure that third countries like the U.K. can take part in contracts financed by the EU loan. Under the Commission’s original proposal, Ukraine can already buy from the U.S. if certain weapons are not available in the EU.

Five diplomats told POLITICO that the effort to open the door to U.K. companies is likely to get strong backing during Wednesday’s ambassadors’ meeting. However, the German proposal is due for a rougher reception.

“This has never been taken seriously, and I don’t see it happening,” said a European Commission official, speaking on condition of being granted anonymity.

Wouter Beke, a Belgian member of the Parliament’s defense committee, stressed that the key is to prioritize Ukraine’s needs and not domestic interests.

“Our first line of defense in Ukraine isn’t served by too stringent clauses on what they could purchase,” he said. “Neither from an exclusive ‘Buy European’ perspective, nor based on a sort of a ‘leaderboard-driven’ mechanism.”