Go back a few years. Imagine a CIA plot to get Iran which considers us the Great Satan and hates us, to declare war on al Qaeda and expend blood and treasure on exterminating al Qaeda – which long ago declared war on us, and which is the most easily defined enemy in our War of Terror. Imagine that al Qaeda might be induced to expend its resources fighting Hezbollah and Iran. Imagine that we could get our enemies to fight each other using whatever weapons they could muster, and expend their blood and treasure on exterminating each other, so that neither had very much to spend on killing Americans.http://www.jerrypournelle.com/chaosmanor/?p=14231
Come to the present, where that is happening. Israel after careful consideration has stayed out of the Syrian civil war on the grounds that the Assad Family has kept the peace with Israel for decades, while al Qaeda attacks Israelis. Imagine that somehow the trick has been made to work, and our enemies fight each other in a war in which the United States has no describable national interest.
Now imagine that having achieved that result we decide to enter the war.