Daniel W. Drezner is a professor of international politics at the Fletcher School of Law and Diplomacy at Tufts University and a regular contributor to PostEverything.
Turkish warplanes shot down a Russian fighter jet after NATO-member Turkey says the plane violated its airspace on the border with Syria. Russian insisted it had not violated Turkish airspace. (Reuters)

When former senator and actor Fred Thompson passed away earlier this month, it was impossible to forget the best line he ever delivered on film:

This line seems particularly trenchant now, as something I worried about last month pretty much just happened:

Turkish military aircraft shot down a Russian jet Tuesday after Turkey says it violated its airspace near the border with Syria, a major escalation in the Syrian conflict that could further strain relations between Russia and the West since Turkey is a NATO member.

Russian officials confirmed that a Russian Su-24 warplane, one of more than three dozen fixed-wing aircraft flying sorties in Syria as part of Russia’s two-month old bombing campaign there, had been shot down but insisted it had not violated Turkish airspace.

Turkey’s military said, however, that the Russian jet was warned multiple times before it was shot down by two F-16 fighter jets.

The Russian Defense Ministry said the plane, flying at an altitude of 6,000 meters, was likely shot down “due to shelling from the ground.” It said it wanted to “stress that the plane was over the Syrian territory throughout the flight.”

The immediate reactions by Turkey and Russia suggest the potential for escalation:

Meanwhile, according to TASS:

Putin called the attack a crime and stressed that Russia would not tolerate it. According to the president, the Su-24 plane crash in Syria goes beyond normal struggle against terrorism, and it is “a stab in Russia’s back delivered by terrorist accomplices.”

“Today’s loss is linked with a stab in our back delivered by terrorism accomplices. I can’t characterize otherwise what has happened today,” the Russian leader said.

And:

So will this business get out of control?

Obviously, it could — but I don’t believe it will. For one thing, Russia and Turkey are sufficiently interdependent that a serious heightening of tensions would severely impair both countries. Turkey would find it very difficult to suddenly stop using Russian natural gas. Russia would find it very difficult to not use the Dardanelles.

On the military side of the equation, as strategically reckless as Vladimir Putin has been, I suspect he would not want to escalate this conflict. Doing so would involve NATO, not just Turkey, and I doubt that Putin wants to get into a war of attrition that would grind away Russia’s air force. Furthermore, there is the pesky problem of the Syria conflict not going away, and Putin’s proxy in Syria still being in grave danger.

Over the next week, here’s what I’d be looking for to see whether this is a new phase of conflict between Russia and NATO or merely a skirmish that doesn’t prove to be a game-changer:

1. Does irrefutable evidence emerge of the SU-24’s location when it was shot down? Although the plane crashed in Syria, its flight path very well may have crossed Turkish airspace. It’s not like Russia has explicitly acknowledged previous reports regarding planes being shot down, but such reports would tend to reduce Putin’s ability to build international support.

2. Does Putin ratchet up tensions elsewhere? If Putin has a modus operandi, it’s to foment tensions in a new region when the situation is worsening in an ongoing area of conflict. So it wouldn’t surprise me if Putin tries to coerce or intimidate the Baltic states soon, as a way of signaling to NATO that Russia has leverage elsewhere. If that happens, it’s a worrying sign.

3. Can Barack Obama lead NATO? Contrary to realist fears, U.S. alliances have not dragged the United States into needless wars. But for alliances to increase security, smaller states must feel that the United States has their back. U.S.-Turkish relations have been, let’s say, “bumpy” in recent years, so it will be interesting to see whether the United States can constrain Turkey from escalating the conflict further. Similarly, if Putin does ratchet up tensions elsewhere, will Obama be able to coordinate a resolute but measured NATO response?

I think we will live through this. But I’m also going to re-read Max Fisher’s Vox essay from this summer, because it seems awfully prescient.