What do Turkey and the Baltic states have in common?
They appear to be part of Russia's strategy of attempting to undermine NATO and expose the alliance's Article 5 selective security guarantee as hollow.
A senior NATO official told the Financial Times that with Turkey "just like in the Baltics, Russia wants to push at NATO's ability to stand behind all its members."
Russia's constant menacing of Estonia, Latvia, and Lithuania in recent years highlighted a thorny dilemma for the Atlantic alliance.
If Moscow sent "little green men" to one of the Baltics to start a hybrid war, NATO would face a difficult choice -- either invoke Article 5 and go to war with Russia or expose the alliance's security guarantees as meaningless.
NATO's recent decisions to deploy troops to the Baltics was a clear effort to create a tripwire and deter Moscow from ever forcing that choice.
But now, the same scenario risks being played out with Turkey as Moscow directly challenges Ankara's interests in Syria.
And the siege of Aleppo appears at least partially designed to increase the flow of refugees toward Turkey.
Russia has also been engaging in psyops aimed at provoking Ankara.
There have been massive military drills in southern Russia and in Crimea.
Stories have been planted in the Russian media suggesting that the downing of a Russian passenger aircraft was the work of Turkish ultranationalists and that Russia is preparing for war with Turkey.
If Russia persists in these provocations, and if Ankara ultimately takes the bait, NATO could soon face the same thorny dilemma on its southern flank that it once feared in the Baltics.