Hindsight is 20-20 and examining events from the perspective of what could have or should have happened is usually an exercise in futility. 

Except when the stakes are high and the path that wasn't taken could have altered our current history.

We've known for years that the CIA was urging President Obama to arm the largely secular Free Syrian Army to give them a chance to overthrow  President Bashar Assad of Syria. This was  before Syria's use of chemical weapons, before Islamic State broke away from al-Qaeda, and before the refugee situation that led to a mass exodus from the Middle East.

In August of 2011, President Obama called on President Assad to "step aside" for the good of the Syrian people. Over the next several months, Obama repeated that call for Assad's ouster. Now, a book to be published this week, reveals a plan supported by most of the intelligence community to overthrow the Syrian dictator and make good the president's words.

But eventually, the president refused and the plan was rejected.

NBC News:

It's long been known that then-CIA Director David Petraeus recommended a program to secretly arm and train moderate Syrian rebels in 2012 to pressure Assad. But a book to be published Tuesday by a former CIA operative goes further, revealing that senior CIA officials were pushing a multi-tiered plan to engineer the dictator's ouster. Former American officials involved in the discussions confirmed that to NBC News.

In an exclusive television interview with NBC News, the former officer, Doug Laux, describes spending a year in the Middle East meeting with Syrian rebels and intelligence officers from various partner countries. Laux, who spoke some Arabic, was the eyes and ears on the ground for the CIA's Syria task force, he says.

Laux, an Indiana native who joined the CIA in 2005 at age 23, says he wrote an "ops plan" that included all the elements he believed were necessary to remove Assad. He was not allowed to describe the plan, but he writes that his program "had gained traction" in Washington. His boss, the head of the Syria task force, regularly briefed members of the Congressional intelligence committees on what Laux was seeing, hearing and suggesting.

A former senior intelligence official said Laux's ideas—many of them shared by other members of the CIA's Syrian task force--were heavily represented in the plan that was ultimately presented to Obama.

But the president, who must approve all covert action, never gave the green light. The White House and the CIA declined to comment.

The White House and CIA leaders "had made it clear from the beginning that the goal of our task force was to find ways to remove President Assad from office," Laux complained. "We had come up with 50 good options to facilitate that. My ops plan laid them out in black and white. But political leadership…hadn't given us the go-ahead to implement a single one."

A couple of caveats:

* Any attempt to overthrow Assad could have resulted in Russian intervention. 

* It wouldn't be enough to overthrow Assad. The entire Ba'ath party political and government structure would have to have been rooted out as well - a possible super-Libya with chaos that would have resulted in all the problems we're experiencing today.

* The civilian opposition council was, at that time, 70% Muslim Brotherhood. Handing the country over to them would have been disastrous.

Would we be better off today if Obama had approved the plan? In all likelihood, ISIS would have split from AQ anyway. Their differences had little to do with the Syrian civil war. The refugee problem may not be as bad today, but it would still be a humanitarian crisis. And armed Islamist militias would be fighting for control of small slices of Syria - much the same situation we are seeing today.

But Assad would be gone and at least the possibility would have existed for some kind of settlement. That's not much to hang your hat on if you favored overthrowing Assad, but it highlights the poor options we've always had in dealing with the Syrian civil war.