However, tensions remain high between the US and Russia, Assad's strongest ally. The Syrian leader's future was expected to be a top issue during a rare face-to-face meeting late today between Obama and Russian President Vladimir Putin. Assad must go, Obama insisted.
"We must recognise that there cannot be, after so much bloodshed, so much carnage, a return to the prewar status quo," he declared during his annual address to the United Nations General Assembly.
Obama rejected Putin's continued support for Assad, saying that simply arguing that the "alternative is surely worse" is not a solution to a crisis that has killed more than 250,000 people since it began in 2011, led to a flood of refugees and created a vacuum for the Islamic State and other extremist groups.
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Russia has long been a major obstacle, shielding Assad from UN sanctions and continuing to provide the Syrian government with weapons.
In fact, Russia has appeared to deepen its support for Assad in recent weeks, sending additional military equipment and troops with the justification that it is helping the government fight the Islamic State.
"There is no other solution to the Syrian crisis than strengthening the effective government structures and rendering them help in fighting terrorism," Putin said in an interview with CBS' "60 Minutes" that aired on the eve of his meeting with Obama.
Summing up his approach to vexing problems, he said that while he wouldn't hesitate to use military force when necessary, the world should not be guided by the philosophy that "might makes right."
Seeking to bolster a focus on diplomacy, Obama noted his administration's efforts to restore ties with Cuba after a half-century freeze and the completion of a nuclear accord with Iran. He noted that Russia partnered with the US to achieve the Iran deal.