Moscow began withdrawing its warplanes from Syria on Tuesday, a day after President Vladimir Putin ordered most forces home after an almost six-month-long aerial onslaught that helped shift the conflict decisively in favor of the Syrian government.
Although there were mixed views about Putin's motives, experts generally agreed that Russia had avoided getting bogged down in a military quagmire in Syria while accomplishing significant goals. The campaign reasserted Moscow's standing as a major international player and solidified the once-tenuous military position of Syrian President Bashar Assad, a Moscow ally.
Moreover, Putin's words were sufficiently vague to allow Moscow to redeploy its air power in Syria if needed.
Russian officials said that hundreds of military personnel would remain behind to staff Moscow's still operational air base and naval facility in Syria. Russia vowed that a scaled-down campaign against terrorism would continue.
"It is too early to speak about a victory over terrorism," Russian Deputy Defense Minister Nikolay Pankov said in a ceremony honoring departing pilots at Russia's Hemeimeem air base in the northwestern Syrian province of Latakia, reported the state-owned RIA Novosti news agency.
Moscow has framed its mission in Syria as a battle against terrorists threatening the Assad government. Assad regards all his armed opponents as terrorists.
An advanced S-400 antiaircraft system will also remain in Syria, along with attack planes and bombers, to "effectively guarantee the security" of remaining troops, Sergei Ivanov, a former defense minister who is now Putin's chief of staff, told Russian television.
Putin's announcement caught governments and observers across the globe off guard and sparked a wave of conjecture about what was behind the decision.
On Tuesday, Kremlin spokesman Dmitry Peskov rebuffed one of the main threads of speculation — that the withdrawal was a sign of a frustrated Putin putting pressure on a stubborn Assad to make concessions in United Nations peace talks. The Kremlin spokesman denied any such motive, though speculation was rampant about a rift between Moscow and Damascus.
"Reading between the lines, it is clear that Russia has grown frustrated by the intransigence and incompetence of the Syrian regime," said a U.S. intelligence official who spoke on the condition of anonymity to discuss internal assessments. "Putin may have propped up Assad in the short-term, but he has also learned firsthand just how hollow the Syrian forces are."
After Putin's announcement, Assad's office in Damascus put out a statement denying any "Syrian-Russian dispute" and saying that Putin's decision did not signal a Russian "abandonment" of the fight in Syria. The move to withdraw Russian forces "was studied with care and accuracy" before being implemented, the statement said, adding that Putin and Assad discussed the pullout on the phone.
Still, the prospect of a Russian withdrawal unnerved some Assad supporters. Reaction was generally muted in Iran, which has been Assad's other principal international backer.
"The Russians have emphasized that they will maintain their bases," Ali Akbar Velayati, a senior foreign affairs advisor to the Iranian leadership, told the conservative Tasnim News Agency. "According to our assessment, the Russians will take up the very important fight against terrorists whenever necessary."
It remained unclear how often Russian aircraft would continue to hit targets in Syria. But the pace was sure to diminish from the peak, when fighter jets and bombers conducted as many as 100 sorties a day in Syria.
On Monday, Putin said that both the Russian naval facility in the Syrian Mediterranean city of Tartus and the Hemeimeem air base would remain operational. The air base was the hub of the Russian assault, which involved about 9,000 sorties between Sept. 30 and this week.
The bombardment helped push back various opposition factions fighting to overthrow Assad, who invited the Russian intervention. Putin said the military had done its job and had helped facilitate the renewal of United Nations-sponsored peace talks that opened Monday in Geneva.
The U.N. special envoy to Syria, Staffan de Mistura, called Russia's decision "a significant development, which we hope will have a positive impact."
Putin's drawdown order became a public relations coup for the Russian president, who was able to portray himself as a peacemaker. The international reaction was generally positive, if guarded.
This week marks the fifth anniversary of the Syrian war, which began with peaceful street protests in March 2011. It soon escalated into a sectarian-fueled civil war that has left much of the country in ruins and forced almost half of Syria's prewar population of 23 million from their homes.
The Syrian turmoil has also produced a new wave of Sunni Islamist radicals who have been blamed for attacks in Paris; Ankara, Turkey; and Beirut, and for the downing of a Russian civilian airliner over Egypt.
One of Russia's stated goals in Syria was to wipe out the 2,000 or so Russian-speaking militants who have signed up for jihad in Syria. Moscow says many have been killed.
Moscow has never specified how many of its service personnel were in Syria, though some unconfirmed reports put the number at about 4,000. The Russian press has reported that about 70 fixed-wing aircraft and helicopters were involved in the Syria campaign.
A Russian senator, Viktor Ozerov, told the private Interfax news agency on Tuesday that as many as 800 service members would remain in Syria, largely to protect the Russian air base and naval facility.
In addition, Russian forces in Syria continue to monitor Syria's partial "cessation of hostilities," which began Feb. 27. Both Russia and the United States are keeping track of reported violations. Russia also has a significant force of drone aircraft in Syria monitoring the cease-fire, authorities have said.
For most of Tuesday, Kremlin-controlled television channels showed the landing of three Su-34 bombers, the first Russian planes to return from Syria after the announced withdrawal. State-run media repeatedly touted the successes of Russia's relatively brief campaign.
"The militants have been pushed out of Latakia, communication with Aleppo restored," one television anchor announced. "Remaining terrorists are being cleared out of Palmyra."
For weeks, Syrian government forces backed by Russian airstrikes have been closing in on the central city of Palmyra, which was overrun last year by militants of Islamic State, the Al Qaeda offshoot. Recapturing Palmyra — home of magnificent, Roman-era ruins — would be a major coup for Assad's government.