Far from the Atlantic and not particularly northerly, the tiny Balkan nation of Montenegro has formally been invited today to join NATO, as part of what the alliance is presenting as an ongoing growth strategy. A nation of 600,000 people, Montenegro first made efforts to secure an invite nine years ago.

NATO last expanded in 2009, with the admission of Albania and Croatia. Montenegro is one of four nations that had been actively seeking membership. Among the others, Bosnia and Herzegovina seems the only realistic potential member, as Georgia’s existing territorial disputes would preclude membership, and Greece doesn’t want to allow Macedonia in because of their name. Ukraine has also recently talked up seeking membership, but similarly has outstanding territorial disputes.

Russia has objected to NATO’s repeated expansions in the past two decades, with those expansions absorbing the bulk of their former Warsaw Pact allies, and sees the continued expansion as a deliberately provocative move aimed at ultimately “surrounding” Russia.

With its accession, Montenegro will be the third smallest active military within NATO, larger only than Iceland and Luxenbourg. With no active warplanes and only two active patrol boats, the addition to the alliance will be trivial to the broader balance of power between NATO and Russia.