Russian troops in Syria moved into a base at Manbij on Tuesday, a day after US forces abandoned it on the orders of President Donald Trump. Brett McGurk, Washington's former special envoy to the international coalition fighting the Islamic State group, tweeted that the decision to withdraw the United States military from Syria was "a gift to Russia, Iran and ISIS."

Russia's modern Middle East intervention

In some sense, McGurk, who resigned over his disagreement with the White House, is right — at least as far as the Kremlin is concerned. When Vladimir Putin went into Syria in September 2015, bailing out Bashar Assad's regime was not his only goal. Putin's main aim was to prove that he can stop what he believed to be a global US policy of changing regimes it did not like. Everything else — securing Russia's military presence in the eastern Mediterranean, testing new weapons systems, proving to the Kremlin's few allies that they can be relied on — was secondary.

In Syria, Putin wasn't so much fighting Assad's enemies as he was Washington. Barack Obama's relative reluctance to get directly involved in the conflict helped the Russian leader establish himself as a Middle East power broker at minimum expense. He "re-inserted" Russia into the region after more than two decades of relative absence to pull weight with Washington on other issues — be it Ukraine, nuclear weapons or NATO enlargement. So, on the one hand, the withdrawal of US forces from northern Syria is a victory for Putin. But on the other hand, that US presence provided the Kremlin with an external partner to talk to in a region where everyone is against everyone else. Not anymore.

Read more: Turkey offensive in Syria forces Russia into a balancing act

A complicated web of friends

The Iranian regime — officially Moscow's closest ally in Syria — has deep suspicions of official Russia. Tehran does not like Putin's close relationship with Israeli Prime Minister Benjamin Netanyahu, one of the few Western politicians who talks to him regularly. The Iranians suspect — correctly, in my view — that if the Israelis decide to confront them militarily, the Kremlin will not stand in the way. They also do not like the fact that with Putin in Syria, Assad can maintain a certain distance from Tehran if he wants.

The Israelis, in turn, are wary of Moscow's close relationship with Iran, including arms deals, a benign attitude towards the Iranian nuclear program and its defense of Iran at international fora such as the UN. Israeli public opinion overwhelmingly considers Putin to be one of Iran's main international enablers. Israel also has massive political and diplomatic clout in Washington, which Putin will never be able to match.

The Saudis, who recently entertained the Russian leader in Riyadh, find their newly minted regular contact with the Kremlin to be a useful tool in easing their dependence on Washington. But for the time being, Saudi Arabia still strongly depends on the US for its defense and considers Russia's ally Iran to be a mortal enemy. Part of Crown Prince Mohammed bin Salman's "courtship" of Putin is an attempt to weaken Moscow-Tehran ties. The Russian president likes this outreach. It boosts his prestige. He is also interested in a relationship with Riyadh because of its leading influence in OPEC. But he abhors the idea of making a choice between the Saudis and the Iranians, should the two come to blows.

Recep Tayyip Erdogan is Russia's most reliable regional ally today. Putin likes the fact that under his leadership, Turkey became what many see as NATO's weakest link. In the Kremlin's scheme of things, little matters more than weakening the alliance. In July, Erdogan stood by his decision to buy the S-400 missile system from Russia, despite Washington's objections. He also no doubt appreciates Putin's silent acquiescence in his ongoing onslaught against the Kurds. But will Moscow be there for him in case the US (especially Congress) decides to put real pressure on Turkey? I doubt it.

Read more: S-400 missile system: What is it and why does Turkey want it?

Leaving might not be so easy

Finally, Putin's own fellow citizens are growing tired of his foreign policy adventures. As Russians' real disposable incomes continue to fall for a fifth consecutive year, 55% of them want the Syrian operation to end as soon as possible, according to the Levada Center, an independent pollster.

Putin is attuned to the shifts in public mood. He is preparing for an uncertain political transition when his fourth presidential term expires in 2024, or even earlier. In such circumstances, to declare victory and leave Syria sounds like a better idea than juggling several "alliances of convenience," each fraught with serious risk. But will Assad survive without Russian support? What will happen to Russia's naval bases if the region plunges into war? Having easily involved himself in the Middle East four years ago, Putin may find it much more complicated to extricate himself and keep his gains intact. Trump's "gift" may turn out to be tricky after all.