(CNN)Five years after President Barack Obama first called for Syrian President Bashar al-Assad to step down, the last American ambassador to that war-torn country issued a scathing criticism of U.S. policy.
Last US ambassador to Syria slams 'myopic' Obama policy
"The United States does not have leverage to forge a consensus," Robert Ford told CNN's Clarissa Ward, sitting in for Christiane Amanpour.
"And, frankly, the Obama administration is doing very little, if anything, to generate leverage to forge that consensus."
Ford said that the administration had a "myopic" focus on ISIS.
"The Islamic State is a problem, but the Islamic State came out of the broader problem of the Syrian civil war. And it really isn't going to be solved outside the context, outside a larger solution to the Syrian civil war."
America is, he said, "trying to fix with a military hammer a deeper political problem."
Ford resigned his post more than two years ago, saying he could no longer "defend the American policy."
He has called for a much more forceful policy against Assad.
U.S. State Department spokesman John Kirby denied the U.S. lacked leverage in Syria.
"Actually, there is leverage," he said. "And Russia is, and has been, part of that leverage in the past. What we want to see is that they continue to live up to those obligations that they have made in so many multilateral forays."
Russia, which said on Monday it was engaged in "very active" talks to begin joint military action with the U.S. over Syria, stepped up its intervention in that country by launching for the first time long-range bombers from an air base in Iran.
Aleppo, Syria's second city, meanwhile remains under partial siege and the target of daily airstrikes.
Speaking with Ward from that city, a British aid worker and activist, Tauqir "Tox" Sharif, said he "couldn't think of enough superlatives to describe the situation."
"We are seeing massacres taking place daily."
Nearly half a million civilians have been killed in Syria, according to human rights groups.