What if China stopped loaning US?

Jim Fallows explained the mechanics of China and the US in a mutually assured destruction-like financial relationship. In this bizarre relationship, if China decides to pull money out the US, both countries lose.
But, at some point China would have to worry about pouring its hard earned money down the American drain. Bloomberg reports on the opening shot; here is an excerpt:

China’s Premier Wen ‘Worried’ on Safety of Treasuries (Update2)

By Belinda Cao and Judy Chen

March 13 (Bloomberg) -- China, the U.S. government’s largest creditor, is “worried” about its holdings of Treasuries and wants assurances that the investment is safe, Premier Wen Jiabao said.

“We have lent a huge amount of money to the United States,” Wen said at a press briefing in Beijing today. “I request the U.S. to maintain its good credit, to honor its promises and to guarantee the safety of China’s assets.”

White House National Economic Council Director Lawrence Summers, asked about Wen’s remarks, said overseas “confidence” in Treasuries would be hurt without the administration’s steps to end the economy’s decline. President Barack Obama is relying on China to sustain buying of Treasuries amid record amounts of debt sales to fund a $787 billion stimulus package.

“China’s purchases of American debt have been one of the few bolts keeping the wheels on the global economy,” said Phil Deans, a professor of international affairs at Temple University in Tokyo. “If China stops buying, where does Obama’s borrowing to fund his stimulus come from?

Change is coming. Soon. And we won't like it.