The intervention entails other risks for Putin going forward. In particular, the United States may decide to challenge the Russian military in Syria. Russia has a preponderance of force along its western borders (with the possible exception of Kaliningrad), but it is exposed in Syria and the eastern Mediterranean, as the recent American missile strikes made clear. It has talked up its S-400 and S-300 air defense systems, but those systems cannot defend the bulk of the territory currently controlled by Damascus and its allies against cruise missiles or U.S. fifth-generation stealth aircraft.

Thus, the United States has escalation dominance in Syria. This means Trump could theoretically embarrass Putin politically by ordering U.S. strikes on Syrian military assets at a time and place of his choosing, even at the risk of killing or injuring Russian military personnel or civilians.

Another risk is that, should Russia witness a surge in jihadist militancy or terrorism at home, the public might blame the Syria intervention. Public support for the war is already limited. A survey carried out by the Levada Center in October indicated that 16% of respondents were “fully positive” and 36% were “probably positive” about Russia’s military operations in Syria. This is considerably lower than support for Putin (82%). A spike in terrorist activity, particularly if carried out by Islamists returning from the battlefields of Syria or Iraq, would undermine the Kremlin’s argument that it is better to fight Islamists abroad than at home. That, in turn, may undermine support for the intervention and, perhaps, eventually for Putin himself.

Finally, Russia faces an “interest asymmetry” problem in Syria. The country is relatively distant from Russia and. Russian-Syrian trade was never significant. Moscow is in no position to help rebuild the Syrian economy, and Russia’s refueling facilities in Tartus aren’t critical to Russian operations in the Mediterranean (which are themselves of limited importance to Russian economic or core security interests). Finally, Russians have no particular historical or cultural affinity with Syrians. American, European, Iranian, and Turkish economic and security interests in Syria are considerably greater.

This asymmetry of interests may prove a serious problem if, as expected, the Russian economy continues to struggle in the coming years. Putin is still very popular, but the government and his regime are not. The Russian public resents what it sees as an undeserving and greedy elite, official corruption, and crony capitalism — attributes of the current order that opposition leader Alexei Navalny has exploited relentlessly. Declining living standards may lead Russians to wonder why the Kremlin is involved a conflict that is far from Russia’s shores and with no clear exit option.

Navalny is already exploiting skepticism about Russia’s role in Syria, as he made clear in a recent interview with The Guardian: “I tell them: ‘OK great, so Putin is promising to rebuild Palmyra, but why don’t you look at the roads in your city?’”

In short, Moscow’s problem in Syria is not unlike Washington’s in Afghanistan and Iraq, albeit on a smaller scale. Despite thousands of lives lost and trillions of dollars spent, there are still 8,400 U.S. troops in Afghanistan, 7,000 in Iraq, and 1,000 in Syria. And in all three theaters, Washington is more likely to increase troop numbers than decrease them in the coming months. Even so, there is no prospect of anything that feels like “victory” to most Americans.

When the Kremlin comes up for breath after March 2018, it may well conclude that entering a forever war in the Middle East was much easier than staying in or getting out.