Sweden applied to join NATO on Tuesday, according to TV4.
The Foreign Minister was filmed signing the application to the military alliance. The application from Sweden will be submitted with that of Finland.
The countries decided to join NATO after Russia invaded Ukraine. Sweden and Finland share a border with Russia.
The countries will no longer be neutral in the face of Russian President Putin's war if they join NATO.
If they joined NATO, Russia has threatened consequences against them. Putin said he was reacting to the potential eastern expansion of NATO.
His invasion of Ukraine prompted political and public support for NATO to grow in Sweden and Finland.
The president of Turkey suggested that he would block their applications to the alliance if they did not get some concessions. A new country can't join NATO if its existing members don't agree with it.
The two countries joining NATO does not pose a direct threat to Russia according to Putin.
His officials have said that Russia may retaliate.
Putin said on Monday that Russia would have to act if NATO moved weapons into Sweden.
During the application period, the prime minister warned that her country would be in a vulnerable position.
She said that Russia will retaliate if we join NATO.