The leaders of Sweden and Finland know they have a fight ahead of them in their efforts to join NATO. US President Joe Biden welcomed them to Washington on Thursday to give them his "full backing."

Biden used the trappings of the White House to show his support for Swedish Prime Minister Magdalena Andersson and Finnish President Sauli Niinisto. He said their countries would make NATO stronger.

Swedes and Finns have maintained a long history of neutrality. The Russian invasion of Ukraine persuaded them to change course.

All 30 NATO members need to approve any new entrant. The leader of one member nation has already said he'll oppose the applications.

The President of Turkey, Recep Tayyip Erdogan, has criticized Swedes and Finns for their support of Kurdish militants, a group he sees as terrorists. Erdogan said his answer to the bids will be "no."