WHEN NATO invited Montenegro to become the 29th member of the military alliance on December 2nd, Russia reacted angrily. It was an “openly confrontational” move, the foreign ministry said in a statement, and Russia would “respond accordingly.” Viktor Ozerov, a senior defence official, threatened to axe joint military projects with the Montenegrins. The Montenegrins were baffled, because there are none. Between Russian rhetoric and action, says Dimitar Bechev, an expert on Russian-Balkan relations, “there is a huge gap.”

A decade and a half after the end of the Serbia-Kosovo war, Russia and NATO continue to vie for influence in the western Balkans. Montenegro’s military is tiny, but its membership means that a small but significant piece of the Adriatic coast has been taken off the chessboard. Its strategic Bay of Kotor (see map) was once home to part of the Yugoslav navy, and to the Austro-Hungarian one before that. Albania and Croatia joined NATO in 2009. Now another gap on the map will be filled.

In 2014 Russian holidaymakers accounted for a whopping 30% of overnight stays in Montenegro, in part because it is the only place on the northern shore of the Mediterranean for which they do not need a visa. Russians have invested heavily here and historic links are more than 300 years old. But none of this dissuaded the Montenegrin government from applying EU sanctions on Russia, which had been triggered by events in Ukraine, when Bosnia, Serbia and Macedonia did not.

Montenegro’s accession to NATO will leave four countries who are nestled among members but are not yet part of the alliance. Macedonia’s ambitions to join have been blocked because of its quarter-century-long dispute with Greece over its name. Bosnia is stymied by internal divisions. Officially Kosovo has no army, but since 1999 its security has been guaranteed by NATO troops. This leaves Serbia, where the alliance is unpopular due to the fact that during the 1999 Kosovo war, NATO aircraft spent ten weeks bombing it.

Officially Serbia is militarily neutral. Serbian troops have held joint exercises with Russian ones in the past two years, and from the media coverage you might think Serbia was equidistant from Russia and NATO. While this might be what the Serbian government wants people to think, however, it is far from the truth.

Last January Serbia signed a co-operation agreement with NATO. Its troops have been training with the Ohio National Guard since 2006. It participates in far more exercises with NATO countries than with Russia. In effect, says Daniel Sunter, a Serbian military analyst, Serbia is now “a very close partner” of the Western alliance. As for commerce, Russia is a major supplier of gas to the region, but otherwise the EU is the dominant trade partner. Russian plans for new gas pipelines through the region have collapsed.

Russia is still making its presence felt in the Balkans. Its government-funded Sputnik agency broadcasts radio and television news in Serbian, in competition with Western outlets. In July, at Serbia’s request, Russia vetoed a British motion at the UN recalling the massacre by Bosnian Serb forces at Srebrenica in 1995. As for Macedonia, in May Russian officials suggested that demonstrations against the Macedonian government were part of a Western plot.

Yet in Montenegro, the government itself in October accused Russia of being behind such demonstrations. Amongst Serbs and Montenegrins, Russia remains popular, but it is very far away. It has been 12 years since Russian troops ceased serving in peacekeeping missions in the Balkans, in 2003; their withdrawal was taken as a sign that they had consigned the area to the Western sphere of influence, says Mr Bechev. Now he says, while Balkan governments will always manoeuvre for the best deals on offer, in terms of security “they will always choose the West.”