The combination of those two policy decisions committed Obama -- albeit half-heartedly -- to the armed overthrow of the Assad regime.
The former administration official confirmed the recollections of both former secretary of state Hillary Clinton and former Pentagon official Derek Chollet that Obama's advisers believed Assad's fall was inevitable.
Some of those advisers believed Assad lacked the "cunning and fortitude" to remain in power, as Chollet put it.
Underestimating Iran and RussiaMore importantly, when Obama was making crucial Syria policy decisions in September 2011, no one on his national security team warned him that Iran had a very major national security interest in keeping the Assad regime in power that could draw the Iranians into the war, according to the former official.
Obama's advisers assumed instead that neither Iran nor Russia would do more than offer token assistance to keep Assad in power, so there was no risk of an endless, bloody sectarian war.
"Both Hezbollah and Iran had made noises that they were displeased with Assad's handling of the crisis, and [Hezbollah leader Hassan] Nasrallah even said publicly he should take a softer approach," the ex-official recalled, "so it was believed Iran would not intervene militarily to save him."
In fact, however, Iran regarded Syria as crucial to its ability to resupply Hezbollah, whose large arsenal of missiles was in turn a necessary element in Iran's deterrent to an Israeli attack. "Syria had been Iran's and Hezbollah's security in depth," the ex-official said, but Obama's advisers "didn't have a clue" about Iran's overriding national security interest in preventing Assad's overthrow by the overwhelmingly Sunni opposition backed by a Sunni international coalition with US support.
That major error of omission become obvious as the war unfolded. After the city of Qusayr near the Lebanese border was taken over by the Free Syrian Army in July 2012, opposition forces in southern Syria were able to get military supplies from across the border in Lebanon. It became clear in the months that followed that al-Nusra Front forces were heavily involved in that front of the war.
Hezbollah strikes backIn May 2013, Hezbollah troops from the Bekaa Valley intervened in support of a regime counteroffensive to retake the city -- obviously at Iranian urging.
That Iranian-Hezbollah intervention resulted in the biggest defeat of rebel forces of the war up to that time.
But instead of questioning the soundness of the original decision to cooperate with the Sunni coalition's regime change strategy, Obama's national security team doubled down on its bet.
Secretary of State John Kerry put strong pressure on Obama to use military force against the Assad regime.
That resulted in a public commitment by the Obama administration in June 2013 to provide military support to the opposition for the first time. The deepening commitment nearly led to a new US war against the Assad regime in September, after the chemical attack on the Damascus suburbs in August 2013.
The Obama administration even agreed to the Sunni states' provision of anti-tank weapons to an armed opposition now openly dominated by al-Qaeda's Nusra Front.
Escalating involvementThat culminated in a Nusra Front-led command's conquest of Idlib province and the subsequent Russian intervention, which the administration's national security team obviously had not anticipated either.
Obama and his advisers blundered on Syria in thinking that they were not getting into a high-risk war situation.
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