Ukraine on Thursday announced that it was closing its airspace to Russian military flights bound for Syria, joining the NATO blockade of arms and military personnel that Western intelligence officials say signals a significant Kremlin buildup in the war-torn Middle East country.
The declaration by Ukrainian officials that Russian planes bound for an airport and Russian naval base on Syria's Mediterranean coast prompted accusations from Moscow that Kiev was capitulating to U.S. orders and in effect aligning the former Soviet republic with terrorist forces in Syria.
U.S. intelligence officials last week told the Los Angeles Times and other U.S. media that recent satellite imagery shows that Russia is infusing the western coast of Syria with arms, military equipment and personnel in what appeared to be preparation for joining the fight to protect embattled Syrian President Bashar Assad and his forces.
On Thursday, the Israeli defense minister told a press briefing in Jerusalem that Russia already has dispatched military advisors and an "active force" charged with setting up an air base in Syria's Latakia province, which is the Assad family's ancestral home.
Russian Foreign Minister Sergei Lavrov was quoted by the Tass news agency as brushing off the reports of a Russian presence in Syria as old news.
"Russian military personnel have been in Syria for many years," Lavrov said. "Its presence is linked with the supplies of weapons for the Syrian army, which is bearing the brunt of the war against terrorism, in particular, the Islamic State, and other extremist groups."
Recent flights to the Latakia region were ferrying in weapons and Russian trainers to instruct Syrian government forces in their use, as well as humanitarian aid, Lavrov said.
Latakia is a stronghold of Syria's Alawite minority, adherents to a Shiite theology that includes the Assad dynasty that has ruled the predominantly Sunni Muslim country for more than 40 years.
NATO member Bulgaria this week closed its airspace to Russian planes headed for Syria, reportedly at the request of the United States. A Foreign Ministry spokeswoman in Sofia said the government had its doubts about the purported humanitarian nature of the Russian aircrafts' cargo.
Greek officials also confirmed that they had been asked by Washington to deny overflights to the Russian aircraft.
A more direct route from Russia to Latakia and the Russian naval base at Tartus would have planes fly over the Black Sea and Turkey. But Ankara forced down a Russian passenger plane three years ago and found it to be carrying air-defense equipment, prompting Moscow to avoid that route when bringing in weapons and supplies for its Syrian allies.
Russia has supported Assad throughout the civil war in Syria, now in its fifth year, and has torpedoed various proposals in the U.N. Security Council to sanction Assad for human rights violations or force him out of power. China has joined Russia in using its veto power to block moves against Assad, fearing that such a precedent could expose Beijing to similar intervention by the world body on behalf of Chinese victims of alleged rights abuses.
Russia's intensified activity in Syria follows months of diplomatic efforts to bring Syria's government and opposition forces together for peace talks and to better coordinate the international coalition targeting Islamic State with airstrikes.
Although Russian President Vladimir Putin's alliance with Assad puts him on the opposite side of U.S. and European states backing opposition forces fighting to depose the Syrian leader, Moscow and Washington share concern about the ascendant power of Islamic State in Syria and its ability to spread violence and disruption across Europe and the Middle East.
After Ukrainian Prime Minister Arseny Yatsenyuk announced that Syria-bound Russian flights would be barred from Ukrainian airspace, the chairman of the Russian parliament's defense committee vowed that Moscow would continue to support the Syrian regime.
"Russia has always managed to devise an alternative solution. It has never abandoned its friends," Adm. Vladimir Komoyedov told Tass news agency. "Ukraine may betray others. Russia will go ahead with its support for Syria and its people."
Leonid Slutsky, the lawmaker overseeing relations between Russia and other former Soviet states for the lower house of Russian parliament, blasted Kiev authorities for what he said was a move that in effect benefits Islamic State extremists by preventing delivery of the weapons Assad needs to fight them.
"Kiev's decision on closing air space for the flights of Russia's planes to Syria has been of course taken upon U.S. instruction," Slutsky said. "Thus, at the instigation of Washington, Kiev turns into an Islamic State associate."