Because war is hell, Brandon, and the hell of war stays with the warrior for the rest of his life and sometimes the results are tragic. When Dubya chose to go to war in Iraq and chose to stay and occupy Iraq he thereby prolonged the war in Afghanistan by giving the Taleban precious time and space to regroup.
The Republicans have compounded this felony by pretending that Dubya wasn't one of theirs and refusing to acknowledge that President Obama has been required to clean up a helluva mess left by Dubya and the GOP.