Finland doubling NATO's border with Russia in blow to Putin

A Finnish soldier participates in the amphibious operations as part of NATO sea exercises BALTOPS 2015 in Ustka, Poland, on June 17, 2015. [AP Photo]

The blue-and-white Finnish flag rises outside NATO headquarters Tuesday afternoon, making Finland a member and doubling Russia's border with the world's biggest security alliance.

The move is a strategic and political blow to President Vladimir Putin, who has long complained about NATO's expansion toward Russia and partly used that as a justification for his country's war with Ukraine.