The questions reflected concerns following the Paris attacks - which killed 129 people - that Obama had missed opportunities to defeat the group when it was gaining strength.
Now Obama is in the unenviable position of championing a strategy that even he admits could take years to work, and could be marked by significant setbacks and more terrorist attacks like those in Paris.
The story of how Obama landed on his approach is one of a President who campaigned for re-election on a promise to end America's wars and came to office with other pressing priorities, such as reaching an agreement that would prevent Iran from acquiring a nuclear weapon.
He was sceptical that US military power could produce lasting political change in the Middle East and heavily influenced by the steep costs and heavy casualties that America suffered in Iraq and Afghanistan.
In the early days of the Syrian civil war, Obama rejected proposals from his top national security advisers at the time, including Secretary of State Hillary Clinton, Defence Secretary Leon Panetta and CIA Director David Petraeus, to arm rebels fighting President Bashar al-Assad's Government.
To Obama, the rebels were a collection of "former doctors, farmers, [and] pharmacists" facing off against a well-equipped Syrian military that also had the support of battle-hardened Hizbollah forces. Early proposals for a no-fly zone that would have grounded Assad's attack aircraft were also dismissed as too costly.
Today, some analysts say Obama underestimated the moderate Syrian forces that were massing against Assad and that they might have been able to pick up support from defecting Syrian military troops if they had shown early success.
Other analysts have faulted Obama for not heeding intelligence suggesting that radical Islamist fighters were becoming the dominant resistance force in Syria.
Senior White House officials have countered that the President's critics vastly overestimate the capacity of American military power to stem chaos caused by decades of misrule and the collapse of repressive governments throughout the Middle East.
To illustrate that point, Obama yesterday described the problems of establishing a safe area for moderate rebels in northern Syria. "Would it become a magnet for terrorist attacks, and how many personnel would be required" to safeguard it, he asked, and most pointedly, "How it would end?"
- Washington Post - Bloomberg