WASHINGTON—President Barack Obama warned Russia Friday against doubling down on its support for Syrian President Bashar Assad, casting a recent buildup of Russian military equipment and personnel in Syria as an effort to prop up the embattled leader.
"The strategy they're pursuing right now of doubling down on Assad is a mistake," Obama said during a town hall with U.S. military personnel.
Russia denies it's trying to bolster Assad and instead says its increased military activity is part of the international effort to defeat the Islamic State, the terror group that has wreaked havoc in both Syria and Iraq. Earlier Friday, Russian Foreign Minister Sergey Lavrov called on world powers to join his country in that pursuit, arguing that Syria's army is the most efficient force to fight the extremist network.
"You cannot defeat Islamic State with air strikes only," Lavrov said, a dig at Obama's strategy. "It's necessary to cooperate with ground troops and the Syrian army is the most efficient and powerful ground force to fight the IS."
Russia's military moves have punctured what had been a notable uptick in optimism among U.S. officials about the prospect that Moscow was tiring of Assad, its longtime ally. Syria has been gripped by civil war for more than four years, a conflict that has claimed more than 250,000 lives and created a vacuum for extremism to thrive.
For months, U.S. officials have been gauging Russia's willingness to help restart a political process to remove Assad from power. Obama, however, painted a grim prospect of that happening in light of Russia's new action.
"It could prevent us from arriving at the political solution that's ultimately needed to bring a peace back to Syria," he said.
Secretary of State John Kerry has spoken twice with Lavrov this week to warn that the Russian military buildup could lead to an escalation of the bloody conflict. The crisis in Syria is also likely to be a major topic when world leaders head to the United Nations later this month for an annual gathering.
Obama and Russian President Vladimir Putin are both scheduled to attend the UN meetings, though it's unclear whether they'll meet. Some analysts believe Russia wants to have its military force in Syria ready for action by the time Putin arrives in New York.
Despite the warnings from the U.S., Lavrov said Russia would continue to supply Assad with weapons that he said will help defeat Islamic State fighters.
"I can only say once again that our servicemen and military experts are there to service Russian military hardware, to assist the Syrian army in using this hardware," he said at a news conference in Moscow. "And we will continue to supply it to the Syrian government in order to ensure its proper combat readiness in its fight against terrorism."
Russia has been a longtime backer of Syria, and it has supported Assad throughout the civil war by shielding him from U.N. sanctions and providing weapons.
Ukrainian President Petro Poroshenko on Friday used the Russian military buildup in Syria to lash out at his country's archenemy, blaming the influx of refugees into Europe on Moscow's support for Assad.
"Today the so-called little green men are landing in Syria, instigating an increase in violence in the Middle East, and provoking a further increase in the number of refugees going to the EU," Poroshenko said at an international conference in Kiev. "Little green men" was the term widely applied to Russian forces in unmarked uniforms who overtook Ukraine's Crimean Peninsula before its annexation by Russia in March 2014.
Russian Foreign Ministry spokeswoman Maria Zakharova responded on her Facebook page, saying Russia isn't trying to conceal the presence of its servicemen who are involved in a "military-technical cooperation with a legitimate government."