WASHINGTON: U.S. President Joe Biden met the leaders of Sweden and Finland on Thursday to advance their applications to join the NATO military alliance, as Turkey repeated its opposition to the move.

Biden, who has lauded cooperation between Europe and the United States in standing up to Moscow during a Russian invasion of Ukraine, stood with Swedish Prime Minister Magdalena Andersson and Finnish President Sauli Niinistö in a sunny White House Rose Garden bedecked with flags.

He cheered the "momentous" day, giving his strong support for the two “great democracies” to “join the strongest most powerful defensive alliance in the history of the world."

"They meet every NATO requirement and then some," Biden said, adding he is submitting paperwork today to the U.S. Congress for speedy approval once NATO approves their accession."

Finland, Sweden hand in applications to join NATO

Turkey has expressed strong opposition to including Finland and Sweden in the alliance, asking Sweden to halt support for Kurdish militants it considers to be part of a terrorist group and both to lift their bans on some sales of arms to Turkey.

All 30 NATO members need to approve any new entrant. Turkish President Tayyip Erdogan said in a video posted on his Twitter account on Thursday that Turkey had told allies that it will reject Sweden and Finland's membership.

U.S. national security adviser Jake Sullivan told reporters on Wednesday that U.S. officials were confident Turkey's concerns can be addressed, and Biden told reporters "I think we’re going to be okay," on the issue.