Nato member Turkey has agreed to support Sweden and Finland's membership of the alliance.
It had initially opposed the Nordic countries' bids to join.
Turkey was angered by what it saw as their willingness to host Kurdish militants. Sweden and Finland could not join Nato without Turkey's support.
Russia strongly opposes the two states joining and has used the expansion of the West's defensive military alliance as a pretext for its war in Ukraine.
But Moscow's invasion has had the opposite effect, with the path now clear for the two countries to join Nato.
Foreign ministers from the three countries signed a joint security pact that addressed Turkey's concerns.
Nato chief Jens Stoltenberg said Sweden agreed to step up its work on Turkish extradition requests of suspected militants.
The two Nordic nations will also lift their restrictions on selling weapons to Turkey, he said.
Finland's President Niinisto said the three countries signed the joint memorandum "to extend their full support against threats to each other's security".
Sweden's Prime Minister Magdalena Andersson said it was "a very important step for Nato".
Turkey President Recep Tayyip Erdogan's office said it "got what it wanted" from Sweden and Finland.
