It was a clash with ominous Cold War overtones. Turkey’s recent destruction of a Russian Su-24 jet was the first time in 63 years a NATO jet shot down a Russian one. Although Ankara claimed the jet was in Turkish territory, Russian President Vladimir Putin accused Turkey of a “stab in the back”and being “accomplices of terrorists.”

Putin subsequently cancelled Russian energy projects in Turkey, and also banned the import of Turkish fruit and vegetables. What Putin said next, though, should send chills down Turkish spines.

In comments during his annual state of the nation speech, Putin implied Russia might use force against Turkey: “We shall remind them many a time what they have done and they will more than once feel regret what they have done,” said Putin. “Our armed forces, secret services and law enforcement agencies have been mobilized to give a rebuff to the terrorist threat.”

While Putin uses bluster for effect — once promising Chechen terrorists Russia would “rub them out in the outhouse” — he does have a legitimate beef with Turkey. Even if the Russian jet was in Turkish territory, it was there for merely 17 seconds, and the Turkish jet fired no warning shots at the Russian one. That Turkish President Recep Tayyip Erdoğan boasted he himself gave the order to fire only made things worse.

In a sign of escalating tension, on Sunday a Russian destroyer fired warning shots at a Turkish fishing vessel. If Putin chooses to further up the ante against Turkey, he’s got a number of cards he could play.

First, Putin could order the Russian military to shoot down a Turkish plane with air-to-ground missiles. The Russian military just deployed its advanced S-400 air defense missile system to the Syrian airbase of Hmeimim, only 18 miles from the Turkish border. This is a military game changer, with even a senior Israeli officer describing its deployment as his country’s “worst nightmare.” With a radius of 250 miles and the ability to target up to 36 aircraft or cruise missiles simultaneously, Russia now possesses the capability to take down a Turkish plane any time it wishes. It also eliminates the possibility that the West could establish a no-fly zone over northern Syria — a step long demanded by Ankara.

Putin also ordered Russian air-to-air fighter jets to accompany its bombers on all flights over Syrian airspace. That’s dangerous because Russia could theoretically shoot down a Turkish jet on the Turkish-Syrian border, and then assert, after the fact, that it was close to attacking a Russian plane. True or not, the Kremlin’s mastery of disinformation could allow the Russians just enough leeway to claim it was self-defense.

Putin could also use the Kurds as a weapon against Turkey. Turkey’s highest priority has always been its fight against Kurdish separatism in Turkey itself, and more broadly to halt the creation of an independent Kurdistan, a state that would theoretically incorporate areas of Iraq, Syria and parts of southeast Turkey.

As part of its anti-Kurdish policy, Ankara opposes the main Kurdish force in Syria, the Peoples’ Protection Units or YPG, as Ankara desperately wishes to avoid the establishment of an autonomous Syrian Kurdish entity akin to Iraqi Kurdistan. For this reason, Turkey recently struck Kurdish positions in northern Syria, and Ankara constantly warns the Syrian Kurds not to scoop up more territory in the area.

Putin could therefore strike a serious blow at Turkey’s geopolitical interests by ordering delivery of more advanced Russian weaponry to the Kurds, some of which would be aimed at Turkey. Syrian Kurds control two enclaves in northern Syria along the Turkish border, and wish to capture the final 60 miles needed to link these two territories together. Although Turkey repeatedly warns it will use force to prevent this scenario, Russian support and encouragement could motivate Syria’s Kurds to take the plunge. This would establish a 400-mile-long anti-Turkish cordon along Turkey’s southern border, which would be nothing short of a disaster in the minds of Turkish leaders.

Arming the Kurds would be a provocative escalation by Moscow, but the strategy still provides the Kremlin plausible deniability — Syria is awash with weapons, after all — and therefore fits Russia’s “hybrid war” doctrine. Russia could also claim that by arming the Kurds it actually cooperates with the West in its fight against Islamic State, since the United States sees Syria’s Kurds as the key local force able to take on the militant group. Indeed, the Kremlin may be laying the groundwork for this approach, as Russian Foreign Minister Sergei Lavrov publicly wondered why Turkey bombs Syria’s Kurds against Washington’s wishes. Putin also suggested that Syria’s Kurds unite with Syrian President Bashar al-Assad to fight Islamic State, an alliance that would upend the entire game in Syria.

Third, Putin could also act to wipe out Turkey’s key allies in northern Syria, such as the Turkmen forces the Russian military started bombing after its jet was shot down. Putin’s vindictiveness towards the Turkmens is clear, as they killed one of the Russian pilots as he parachuted down, and then released a video showing them cheering and yelling “Allahu Akbar” as they found the body. Turkey, though, counts on allies like the Turkmen to secure itself a seat at the table when negotiations between Assad and opposition forces sit down to discuss Syria’s future early next year, so the Russian destruction of Turkmen forces would be another strategic setback for Ankara.

Finally, Putin could make mischief for Ankara within Turkey itself. Russian agents have previously killed alleged terrorists in Turkey, and appear to have done so again just last month. This continues a broader pattern where anti-Russian figures from the North Caucasus are executed in Turkey. In a worst case scenario, Russia could further escalate within Turkey by providing support directly to the Turkish PKK, which has been fighting against Ankara’s forces in southeastern Turkey for decades.

While Russia certainly could hurt Turkey, Ankara has cards of its own. In particular, it could close the Turkish Straits. Russian ships have traversed the Straits unimpeded for decades, but under the 1936 Montreux Convention, Turkey is allowed to close the Straits in a war with Russia or if it considers itself to be “threatened with imminent danger of war.” This would bottle up Russian ships in the Black Sea, and significantly increase the difficulty for Moscow to resupply its forces in Syria. Turkey has already created “delays” for Russian cargo ships travelling through the Straits — a clear warning from Erdogan.

To be sure, calmer heads may still prevail, and Moscow-Ankara tensions will likely subside over time. Given that the Turks have fought and lost 17 wars against Russia since the 15th century, Ankara likely hopes this is the case.