In 2007, he was the anti-war presidential candidate, telling crowds on the campaign trail that "we continue to be in a war that never should have been authorized." But six years later, President Barack Obama found himself in a position he probably never thought he would have to occupy: standing behind a podium in the Cross Hall of the White House, telling the American people they were going back to war with Iraq.

President Obama's address Wednesday night -- in which he laid out his plan to defeat the Islamic State by initiating airstrikes in Syria and sending 475 additional military advisers to Iraq -- was the product of two very powerful motivators, explains Charles M. Sennott, co-founder of GlobalPost and head of the GroundTruth Project.

First was emotion. The grotesque horror of seeing the murders of American journalists James Foley and Steven Sotloff by the militants has spurred even a war-weary American public toward supporting military action. Second was logic: the Islamic State has metastasized into a dangerous, well-armed and well-funded organization. "We cannot allow them to take root," Sennott says.

But the specter of America's past foreign policy mistakes will haunt the newest phase of the Long War, Sennott predicts. Had the Obama Administration followed through on its threat to react more decisively against Syria when the Assad regime crossed the "red line" of chemical weapons usage, the Islamic State may not have been able to take root in Syria and Iraq as it has. On a smaller scale, failure to work with allies in the region like Turkey left critical borders porous and therefore easily crossed by foreign fighters looking to join the insurgents. "The mistakes made earlier have raised the stakes now," Sennott says.

Despite President Obama's adamant promise that renewed military action in the Middle East will not include American troops on the ground, Sennott is skeptical that he will be able to fully achieve his goals -- degrading and ultimately destroying the Islamic State -- without it. And either way, an end to the conflict will not come quickly.

"It needs to be underscored that the President just made his legacy that he will hand over a new front in the Long War to the next President," Sennott says.

"This is years," he continues. "This is not months. This is years."

You can read more of Charles Sennott's take on President Obama's address here