<p>Back in 2012, President Barack Obama issued a statement at a news conference that would change his presidency and his legacy forever.</p><p>It was a year into what would become Syrian leader Bashar Assad’s brutal and protracted war on his own people, a war that would cost hundreds of thousands of lives, empower Iran and Russia and destabilize much of the region.</p><p>Obama said then of U.S. intervention, “We have been very clear to the Assad regime, but also to the other players on the ground, that a red line for us is we start seeing a whole bunch of chemical weapons moving around or being utilized. That would change my calculus.