Russian jets are only a few days into their bombing missions in Syria, and they are already causing wider trouble in the region: On two separate incidents, the jets have crossed into Turkey's airspace.

The incursions were brief but appear to have been deliberate. "The information, intelligence that we have received provides me with reasons to say that this doesn't look like an accident," Jens Stoltenberg, the secretary-general of NATO, said. Russia has called it a mistake.

This is dangerous. Turkey scrambled jets in response, and while it surely doesn't want a war with Russia, this is precisely the kind of incident that can spiral out of control. "Had Turkey responded," Secretary of State John Kerry warned, "it could have resulted in a shootdown, and it is precisely the kind of thing we warned against."

Turkey is a member of NATO, meaning that the other members of NATO — the US and much of Europe — are obligated to come to Turkey's defense if it's attacked. In other words, if Turkey and Russia end up shooting at one another over some misunderstanding at their border, it could escalate into a full-blown war between the world's top nuclear powers.

To be clear, the odds of this happening are very, very low. But the potential stakes are high enough to make it worrying all the same — especially because there's every reason to expect these Russian flights will continue bumping into Turkish airspace.

Why are Russian jets buzzing Turkish airspace?

This is something that Russia has been doing for some time in another part of the world: along the Baltic states of Estonia, Latvia, and Lithuania, which are on Russia's border and are also NATO members. The Russian flights starting crossing near or into their borders shortly after Russia covertly invaded eastern Ukraine, which prompted European and American sanctions on Russia.

Based on that precedent, there are a few plausible reasons for why Russia would now be buzzing Turkish airspace as well, despite — or, more likely, because of — the risks that carries.

The first and most important reason — and a reason that Americans, who often overhype Russia's threat, tend to forget — is that Russia knows its military is much weaker than America's and NATO's. This is something you hear Russian defense officials say constantly; this knowledge of their relative weakness is world-shaping for them.

So one way Russia has dealt with its relative weakness is by being more provocative, by demonstrating its willingness to raise the stakes and toe ever closer up to the line of outright conflict. The message the Russians want to send isn't that they'll deliberately start a war with the West — they won't — but rather that they're more willing to take on risk, and so if the West doesn't want the headache it should just back down.

In terms of Syria, then, this is about Russia finding a way to assert its military presence, and preempt any Western effort to chase it off, by taking pushy and provocative steps like buzzing Turkish airspace.

Could this be about deterring an American no-fly zone?

There's another plausible, related reason: Russia wants to raise the cost of any Western efforts to bomb Syrian leader Bashar al-Assad's forces or impose a no-fly zone over Assad-controlled areas of Syria. Those areas are about where the Russian flights into Turkish airspace occurred. The more that Russia can be provocative and unpredictable over Assad-controlled territory, the less willing Western powers will be to send their own jets into those areas or to establish anti-Assad airstrikes or a no-fly zone.

The Americans, Russia is perhaps hoping, will see that Russia has made it riskier to fly over Assad-controlled territory, and thus will be less likely to bother. That's not because they fear Russia will deliberately fire on them, but rather out of a fear that Russia's provocations will increase the risk of an accident. So for Russia, the risk of an unwanted escalation isn't a bug — it's the whole point.

And then there's another possible factor here: On some level, this is perhaps just how the Russian military operates. Even if Russian President Vladimir Putin did not personally order the Russian jets to fly into Turkish airspace, he has helped cultivate a military culture that encourages this sort of conduct, so it's plausible that this was ordered rather by a high- or even midlevel commander who thought it was in line with Russia's grander strategy.

Still, whatever the strategy, it promotes the already worrisome risk of an accident or unintended escalation that could push Russia and NATO, including the US, closer to direct conflict. That risk is probably still higher in Eastern Europe than it is in the Middle East, where Russia has a much smaller military presence, but with US and Russian jets bombing over the same country for the first time since World War II it is a serious enough risk to consider.

Meanwhile, this is having the more immediate effect of enraging Turkey — normally one of NATO's friendliest countries toward Russia — and growing the ever-widening global backlash against Russian actions. That all makes Putin's already doomed Syria intervention even more self-defeating, but it does not remove the risk of an accident or unintended escalation that could spiral out of control.