Secretary of State Antony Blinken gave that assurance in a letter sent Thursday to his Danish and Dutch counterparts, Reuters reported.

"I am writing to express the United States' full support for both the transfer of F-16 fighter aircraft to Ukraine and for the training of Ukrainian pilots by qualified F-16 instructors," Blinken wrote to the officials, Reuters reported, citing access to a copy of the letter.

"It remains critical that Ukraine is able to defend itself against ongoing Russian aggression and violation of its sovereignty," Blinken added.

Ukraine has actively sought F-16s from the U.S. and other Western allies to help beat back Russia's offensive.

As recently as Wednesday, Ukrainian officials were not optimistic about getting the fighter jets anytime soon.

"It's already obvious we won't be able to defend Ukraine with F-16 fighter jets during this autumn and winter," Ukraine Air Force spokesperson Yurii Ihnat said in a state TV appearance.

Earlier this month, The Washington Post reported it would be next summer before the fighter jets made their way to Ukraine.

President Joe Biden endorsed F-16 training for Ukrainian pilots back in May.

But amid the pledges, the West has proceeded cautiously, concerned about provoking a direct confrontation with Russia.