Imagine this scenario, as described last week in Washington by defense expert and former Senator Gary Hart.

Overnight, Iraq has descended into a full-scale civil war. Shiites and Sunnis are viciously killing each other. Vying for supremacy, both groups come after American troops–who are unable to take sides or quell the violence. Stuck in urban centers, US soldiers are unable to safely flee in time. A bloodbath ensues.

"America could lose its Army in Iraq," Hart told a crowd of journalists and foreign policy junkies at the New America Foundation last Thursday, repeating the warning twice. "See Black Hawk Down and multiply it to the tenth power. Read the history of 1812. Think of the image of US soldiers on helicopters [exiting] Saigon and multiply it to the tenth power."

Remember, Hart’s January 2001 report with former Senator Warren Rudman famously predicted a 9/11-style attack on US soil. Where is the Pentagon’s contingency plan for such a nightmare Iraq scenario, Hart wonders? Does it even have one?

"I know that sounds apocalyptic, but it’s not out of the question," Hart remarked at another event in DC that day. "We need an exit strategy. We have no choice."