On the 65th anniversary of NATO, the debate over the organization’s expansion remains highly contentious, with some viewing it as a broken promise to Russia after the fall of the Iron Curtain.

NATO, an intergovernmental military alliance based on the North Atlantic Treaty, was signed on April 4, 1949 when the US, Canada, Portugal, Italy, Norway, Denmark, and Iceland joined the members of the Treaty of Brussels to form the North Atlantic Treaty Organization.