The Senate approves treaties and must consent to bringing new members into NATO.

Senator Bob Menendez, who heads the Senate Foreign Relations Committee, told a hearing that the panel "is already working to ensure swift consideration" for both Finland and Sweden if either applies.

The committee's top Republican, Jim Risch, called Finland's announcement "a tremendous step forward in the future of transatlantic security."

"The decision to move toward NATO membership is a serious one, and I extend my commitment to support Finland through this process," Risch wrote on Twitter.