BRUSSELS (AP) — The European Union's foreign policy chief said Tuesday that the U.S. green light to allow Ukrainian pilots to get training to fly F-16s has created an inexorable momentum that will inevitably bring the fighter jets to the Ukrainian battlefield.

"You know, it's always the same thing: we discuss, at the beginning everybody is reluctant," said Josep Borrell, giving the example of the long debate and initial opposition to the dispatch of advanced Leopard battle tanks to Ukraine.

"And at the end — with the Leopards, with the F-16 at the end — the decision comes to provide this military support because it is absolutely needed."

NATO Secretary-General Jens Stoltenberg confirmed that the training decision was the exact thrust necessary toward making the jets available to Ukraine.

"Announcing clearly that they will start training — this is an important step that partly will enable us to deliver fighter jets at some stage," Stoltenberg said before meeting with EU defense ministers. He said it also proved that the West wouldn't stand down in the face of Russia, saying such a decision "is sending a very clear signal that we are there for the long term and that Russia can not wait us out."

Borrell added that training for Ukrainian pilots had already begun in Poland and some other countries, though authorities in Warsaw couldn't immediately confirm the news. The Netherlands and Denmark, among others, are also making plans for such training.

No decision on actually delivering fourth-generation fighter jets has been taken yet, but training pilots now — a process that takes several months — will help speed up battle readiness once a formal decision is made.

"We can continue and also finalize the plans that we're making with Denmark and other allies to start these these trainings. And of course, that is the first step that you have to take," Dutch Defense Minister Kajsa Ollongren said.

"We will continue discussing with our allies and with countries that might have F-16s available about that next step. But that's not on the table right now," Ollongren said.

Ukraine has long begged for the sophisticated fighter to give it a combat edge as it battles Russia's invasion, now in its second year. And this new plan opens the door for several nations to supply the aircraft and for the U.S. to help train the pilots.

With the decision, the Biden administration has made a sharp reversal after refusing to approve any transfer of the aircraft or conduct training for more than a year because of worries that it could escalate tensions with Russia. U.S. officials also have argued against the F-16 by saying that learning to fly and logistically support such an advanced aircraft would be difficult and take months.