The so-called, "80%' or "tilt" strategy advocates the United States declare reconciliation between Sunni and Shiite impossible and throw our support behind the Shiite majority. It's a possible path the administration discussed recently. While it does seem like a faster method of settling a violent and bloody fight, it has enormous costs of its own. Drum explains two possible types of fallout.
A. Complicity in slaughter.
It's hard to believe that anyone is taking this seriously. If reconciliation with the Sunni minority is impossible — and it probably is — then we should withdraw and let the Shiite majority take over. The result would be bloody, but at least we wouldn't be involved. The alternative being mooted here would put us directly on the Shiite side, and we'd be viewed as actively cooperating with a massacre of the Sunni minority no matter how hard we protested otherwise. It's hard to imagine a more disastrous end to a disastrous war.
B. The Saudi regime (which is Sunni) decides to make it very, very hard for the U.S. In an op-ed in the Washington Post an advisor to the Saudi government laid out their potential reaction to a U.S. backed Shiite majority: funding, arms and logistic support to Sunni military leaders in Iraq. He also tosses in the threat of action on the oil front; causing the price to tank. A direct attack on both Iran and U.S. oil companies. Drum speculates this is what Vice President Cheney was summoned to Riyahd for.
Neither option bodes well for the U.S. or Iraq.