The United States should renounce military commitments to Taiwan to avoid a potentially costly conflict if the island declares independence from China, said the author of book which warns of a U.S.-China war within the next decade.

Defending Taiwan from the attack China threatens to unleash in the event of an independence declaration is "a bridge too far" for the United States, said Ted Galen Carpenter, vice president for defense and foreign policy studies at the Cato Institute, a libertarian Washington think tank.

Rather than promising to defend Taiwan, Carpenter said, Washington should step up arms shipments to help the old U.S. friend defend itself.

His book, "America's Coming War with China : A Collision Course over Taiwan," says the United States stands between two inexorably opposed forces an unfinished Chinese civil war.

"There may not be a way to avoid a collision between Taiwan and China, unless one side or another blinks," Carpenter told Reuters in an interview. "What the United States needs to do is to get out of the middle of that quarrel."

A war between the United States and China could erupt by about 2013, the estimated date China would be militarily capable of seizing Taiwan, Carpenter says in the book. An attack on Taiwan could draw in the United States because it has given defense assurances to the island.

"At some point either Taiwan provokes Beijing beyond endurance or Beijing decides the time is right to settle this issue on Chinese terms," Carpenter, a frequent author on military issues, said in the interview.

"Given the trends on Taiwan and the mainland, I think a collision is very likely at some point within the next decade," he said.

Chinese President Hu Jintao will visit the United States next week and is expected to press President George W. Bush to do more to rein in Taiwan, which has angered Beijing by taking symbolic steps to play down the island's ties to the mainland.

"President Hu is likely to be disappointed if he expects a forceful statement from the United States," said Carpenter.

Taiwan has been divided from China since 1949, when fleeing Nationalist forces turned the island into a stronghold against the mainland's new Communist rulers.

China says it will use military force if Taiwan declares independence. The United States accepts Beijing's "one China" policy, but provides arms to help defend Taiwan.

Carpenter's book argues that U.S. policy sends mixed signals by courting China for business opportunities and diplomatic support while offering protection to Taiwan, a democracy with many friends in the U.S. Congress.

Withdrawing the U.S. defense commitment "will be a very hard sell politically," Carpenter acknowledges. But he says more robust arms sales to Taiwan might provide cover for Washington to back away from a pledge of direct involvement.