Russia said it held Turkey accountable for the drone attack, calling it a breach of their cease-fire agreement in northern Syria, while Turkey accused Russia and Iran of jeopardizing the entire peace process by launching an offensive to take control of an opposition-held air base in the area.
The Russian Defense Ministry named the opposition-controlled village of Muwazarra in southern Idlib province as the location from which a swarm of at least a dozen drones armed with crude explosives was launched Saturday, attacking the Hmeimim air base and the nearby naval base of Tartus in northwestern Syria. Under the cease-fire deal, Turkey is supposed to restrain opposition forces in Idlib province.
The Defense Ministry posted photographs of one of the drones on its Facebook page, showing what looked like a homemade model aircraft that did not seem particularly sophisticated.
The fixed-wing drone resembled an oversize toy aircraft and appeared to have been cheaply assembled from a type of plywood, said Aaron Stein of the Washington-based Atlantic Council. The craft was attached to the kind of engines used to power lawn mowers and strapped with at least nine small rockets that could have been dropped from the drone or used to turn the craft into a bomb.
It was unclear from the photographs how the drones were guided, but simple GPS devices could conceivably have been programmed to fly the planes over a long distance to reach the air base, using GPS coordinates available on the Internet, Stein said.
"The drones look to me like a DIY project, and decidedly low-tech," he said.
The drones nonetheless represent the first time such a weapon has been used in Syria in this way.
Six days earlier, two Russian servicemen were killed in what was widely reported as a mortar attack on the Hmeimim base. At least some fighter jets in Russia's fleet also appear to have been damaged in the attack. But increasingly there are suspicions that the attack also may have been carried out with weaponized drones.
Neither of the attacks has been claimed, heightening the mystery around who was responsible.
The Islamic State has used commercially available quad-type drones to drop small quantities of explosives on enemy troops in Syria and Iraq, but those devices have a range of no more than one to two kilometers, according to the IHS Markit consultancy group.
Russia says the drones used in the attacks had a range of about 30 to 60 miles and on Wednesday said they were launched from the village of Muwazarra, about 50 miles from Hmeimim. The village is controlled by the "moderate opposition," said a report in Russia's official Defense Ministry newspaper.
Residents of the village in the Jabal Zawiya mountains said they had no knowledge of the attack and expressed fear that Russia would retaliate against them. "We reject the Russian accusations completely," said Mohanned Issaf, 27, who lives in the village and was contacted over social media. "The village has always come under shelling, and the regime and Russia don't need an excuse to bomb us. But now they might bomb more after these false accusations."
Muwazarra has been on the front line of the war between rebels and forces loyal to President Bashar al-Assad since the earliest days of the war, when the region quickly came under the control of U.S.-allied moderate rebels with the Syrian Revolutionary Forces.
But after the al-Qaeda affiliate Jabhat al-Nusra drove the SRF out of the area in 2014, it has been under overall control of the extremists. The village remains loyal to the moderate opposition, but military positions surrounding it belong to the Nusra offshoot Harakat Tahrir al-Sham, or HTS, said another man who lives in the village and did not want his name to be used. The closest HTS base, lying in a valley to the east of the village, was destroyed in a Russian airstrike earlier this week, he said — after the attacks on Hmeimim.
The HTS is a possible suspect in the drone attack "because they are the biggest and strongest of the opposition groups" in the area, said Aron Lund, who analyzes Syria for the Century Foundation. If they were responsible, it is not clear why they would not claim the attack.
Many Syrians and also Russians have speculated that foreign intelligence agencies with reasons to provoke the Russians may have helped a local group conduct the attack. "There's a lot of fishy stuff going on in Idlib — agents running around, and groups working with groups they shouldn't work with," Lund said. "It's very, very murky."
In a letter sent to top Turkish officials, Russia said it held Turkey responsible for the drone attacks, which it described as a breach of their cease-fire deal in Idlib province, according to the Defense Ministry newspaper. Under an understanding reached between Russia, Turkey and Iran last year, Turkey is supposed to be responsible for restraining the opposition in Idlib and Russia and Iran is responsible with preventing the regime from carrying out attacks.
The Hmeimim attacks coincide with an escalation of fighting in Idlib, with a new offensive that was launched by the Syrian government, backed by Russia, now underway.
Turkish Foreign Minister Mevlut Cavusoglu complained Wednesday that Iran and Russia were not upholding their agreements under the cease-fire and called on them to halt their offensive.
The outlines of a potential new deal appear to be emerging under which Russia agrees to prevail upon the Syrian government to refrain from attacking any more opposition territory and Turkey agrees to prevent the opposition from attacking Russian bases, said Jennifer Cafarella of the Institute for the Study of War.
Zakaria reported from Istanbul.