It’s been two months since the first Russian tanks rolled across the Ukrainian border. The unprovoked invasion has Finland and Sweden wondering if their own borders are secure. They may join NATO to provide that security.

NATO was formed in 1949 to protect Europe and other Western nations from what was then the Soviet Union. Canada, the U.S., and 28 European countries belong to this powerful military alliance. Under Article 5 of the pact, an attack on one NATO member is considered an attack on all.