The war in Ukraine has upended the security policies of major powers worldwide. Sweden and Finland, both of which followed a security policy of neutrality throughout the Cold War and maintained this posture when it ended, filed applications to join Nato on Wednesday.

The announcement that they had applied to join Nato, a 30-member military alliance led by the US, is significant. It reverses a policy of neutrality maintained by the two countries for seven decades since the end of World War 2. ..