Ukraine has received the first F-16 fighter jets that it has sought for months to fight back against an onslaught of Russian missile strikes, a U.S. official confirmed to The Associated Press.

A Ukrainian lawmaker also confirmed Ukraine had received a small number of F-16 fighter jets. The two officials spoke on the condition of anonymity because they were not permitted to speak on the subject publicly.

Ukraine has been pushing its Western allies for F-16s for Ukraine for months, saying they were critically needed to fight back against the onslaught of missiles Russia has fired against it. The F-16 is specialized in suppressing enemy air defenses. The West has hesitantly moved toward providing the jets, after previous concerns that arming Ukraine with advanced weaponry would further escalate the war with Russia.

The U.S. has also been training Ukrainian pilots on how to fly the jets and has already graduated the first group of pilots on its operation.