Imagine that you lead a small Balkan country that ardently aspires to join Western institutions. But your country also has long-standing cultural and economic ties to Russia, akin to those that have riven Ukraine in recent months. Then, the West imposes sanctions on Moscow and you are pushed to choose: Are you with the West, or against it?

If your country is Serbia, the largest state in the former Yugoslavia, you claim neutrality, refusing to join the sanctions regime crafted by Brussels and Washington, despite the fact that you have a pending application for membership in the European Union. On the other hand, if you are the leader of tiny Montenegro, you stand with the West and agree to impose the sanctions in the face of withering criticism from Moscow.

Yet following this courageous display of solidarity, Montenegro has received very little appreciation from the NATO alliance, the organization that continues to play a vital stabilizing role in the Balkans despite, for the most part, deploying few troops. For the recently independent and still vulnerable countries in the region, NATO membership delivers both external and internal security, severely curtailing the potential for interethnic strife while anchoring new members in Western democratic values. Although it had been conducting membership talks with Montenegro for five years, NATO has decided to once again postpone the country’s admission. In a baffling display of short-sightedness, key European capitals are willing to expose not only Montenegro but also neighboring Bosnia and Macedonia to Russia’s opportunism, risking potential regional instability.