Shiites and Sunnis can't get along for a long enough time to form any kind of strong alliance.
Actually, when it comes to hating us, they seem to be allied just fine. Osama has even called on his rivals to join with him, and I think our reliance on the hatred of various Islamic factions for each other is very much mistaken. The enemy of my enemy is my friend, and all that.
Don't forget the truth of the old adage: the enemy of my enemy is my friend. Differences have been put aside to promote the international terrorist jihad against the West.
The Chicoms follow a long Communist tradition of exploiting these sectarian and regional interest groups to serve as their proxies against their principal global opponents - us!
It's not even too far fetched to think of the Chicoms or North Koreans aiding and abetting Iran's nuclear quest. It's already been documented by the Israelis that some of Hezbollah's arsenal originated in China.