Fresh from a visit to China, the new commander of U.S. military forces in the Pacific and Asia said he found Chinese military leaders intensely interested in acquiring aircraft carriers. At the same time, Adm. Timothy Keating said: "I suggested let's not be naive about the complexity of those ships, and they are not cheap."

The admiral, a naval aviator who has made 1,200 carrier landings, said all of the Chinese leaders with whom he spoke during a five-day stay earlier this month indicated their inclination to pursue the development of aircraft carriers. "No one said we're not going to do this," he said in an interview at his Pacific Command headquarters overlooking Pearl Harbor.

Keating declined to speculate on when China might start building a carrier, but noted that it took the U.S. Navy, even with the most extensive experience in the world, more than a decade to design, build, equip with aircraft, and train both air and ship crews.

"This would be a profoundly difficult venture if the Chinese choose to undertake it," he said.

The U.S. Navy had nearly 800 planes crash in training accidents in 1954 during the transition from propeller driven aircraft to jet aircraft, say Andrew Erickson and Andrew Wilson, who are on the faculty of the U.S. Naval War College in Newport, R.I. Even as late as 1999, the Navy lost 22 planes flown by the world's most experienced aviators.

Internal discussion and external speculation over China's acquisition of an aircraft carrier has been churning along for at least 25 years but now seems to have picked up momentum. Keating said he sensed that, just below the surface, the Chinese saw aircraft carriers as potent symbols of great power status, a clear Chinese aspiration.

On a related score, the U.S. Pacific commander continued making a point cited by several predecessors, cautioning his Chinese hosts not to misjudge American military capacity or intentions. He urged that both Chinese and Americans "take all prudent measures to avoid miscalculation or misunderstanding."

"We were not bellicose about it," he said. Rather, he said, "let's make sure we don't get into situations where there would be recourse to military force."

An early Chinese advocate of aircraft carriers was Adm. Liu Huaqing, from the time he became chief of the Chinese navy in 1982 until he retired as a vice chairman of the Central Military Commission in 1997.

"To modernize our national defense and build a perfect weaponry and equipment system," the admiral once wrote, "we cannot but consider the development of aircraft carriers."

So far, the Chinese navy has concentrated on buying submarines from the Russians or building them at home. That policy, however, will most likely not last much longer, Erickson and Wilson said.

"While submarines seem to be ascendant," they wrote last fall, "the Chinese are still actively engaged with the carrier question and are reframing the terms of the debate." They suggested that China could include carriers in their next five-year plan, which begins in 2011.

There appear to be five reasons China may buy or build a carrier: