The addition more than doubles the length of the 1,215 kilometers of borders that NATO member nations share with Russia. Finland and Russia share a 1,340-kilometer border.
NATO's preliminary analysis suggests the incident was likely caused by a Ukrainian air defense missile fired to defend Ukrainian territory against Russian cruise missile attacks.
In Warsaw, ministers from Central and Eastern Europe warily eyed Russia’s military activities. In Washington, where NATO was born, China was foremost on the list of concerns.