ULAN BATOR, Mongolia » When Robert M. Gates visited China in 2011 as U.S. defense secretary, the military greeted him with an unexpected and, in the view of U.S. military officials, provocative test of a Chinese stealth fighter jet, a bold show of force that stunned the visiting Americans and may even have surprised the Chinese president at the time, Hu Jintao.

When Defense Secretary Chuck Hagel visited China this week, the military greeted him with a long-sought tour of the country’s lone aircraft carrier, the Liaoning, in what many U.S. officials interpreted as a resolve to project naval power, particularly in light of recent tension between Beijing and its neighbors over disputed islands in the East and South China Seas.

The displays of China’s military power reveal some dividends from years of heavy investments, and perhaps a sense that China is now more willing to stand toe-to-toe with the Americans, at least on regional security issues.

But U.S. officials and Asia experts say the visits also showed a more insecure side of China’s military leadership — a tendency to display might before they are ready to deploy it, and a lingering uncertainty about how assertively to defend its territorial claims in the region.

Hagel encountered both combative warnings in public forums and private complaints that Beijing felt besieged by hostile neighbors, especially Japan and the Philippines, which it asked the United States to help address. The impression for some U.S. officials was that China still has not decided whether it wants to emphasize its historical status as an underdog or adopt a new posture as a military powerhouse.

On the tough side, China’s defense minister, Gen. Chang Wanquan, announced that his country would make "no compromise, no concession, no treaty" in the fight for what he called its "territorial sovereignty."

"The Chinese military can assemble as soon as summoned, fight any battle, and win," he said.

But the tough stance belies a different reality on the ground, a military with little or no combat experience, outdated or untested equipment and a feeling of being under siege. The Liaoning, according to U.S. defense officials who toured the ship, still lags well behind the United States’ 10 aircraft carrier groups.

While Hagel spoke expansively about how impressive he found the Chinese sailors he met aboard the ship in his public remarks, one U.S. defense official who accompanied Hagel noted privately that the Liaoning was "not as big, it’s not as fast," as U.S. carriers. Some experts on China were more dismissive. The Liaoning is "a surplus ship from the Soviet era that had been used as a hotel after it was decommissioned," said Andrew L. Oros, an associate professor of political science at Washington College in Chestertown, Md., and a specialist on East Asia.

"In my view this is about national pride, about being on the cusp of being able to challenge the powers that wrought such destruction and misery on China in the 19th and 20th centuries," Oros said. "I think this leads them to over-flaunt, both out of genuine satisfaction in being able to do so, but also as a domestic crowd-pleaser."

In Beijing, standing next to Hagel at the Defense Ministry this week, Chang likened himself to the U.S. defense secretary, who has two Purple Heart medals from combat during the Vietnam War. "Secretary Hagel and I are both old soldiers who fought on the battlefield," he said, prompting a number of raised eyebrows among the Americans in the room. "We have a deep understanding of the atrocities of war."

That may be so, but no one in China’s political or military leadership, which has focused for three decades on national economic development, has significant experience in war, and its troops are not trained in combat. Even Japan, which eschewed combat after World War II, is believed by U.S. officials to have a superior navy, one that regularly trains with U.S. Marines and sailors and with a technical sophistication that counterbalances the heavy investment China has made in recent years.

In private meetings with Hagel, Chinese officials sounded more defensive, U.S. officials said, expressing frustration over what they presented as a Japan and a Philippines made bolder by their treaty alliances with the United States, and ganging up on Beijing.

The U.S. response, that the United States takes no position on competing claims for disputed islands in the East China Sea — which the Japanese call Senkaku and the Chinese call Diaoyu — or the islands and reefs claimed by the Philippines in the South China Sea, seemed only to further inflame the Chinese. Beijing also objects to the standard Obama administration line that the United States has treaty obligations to Tokyo and Manila.

Beyond that, U.S. officials say the stronger public statements by leaders of the People’s Liberation Army are aimed partly at the Chinese public at large, noting a headline in the China Daily newspaper on Wednesday that spoke of Hagel’s being "urged" by Chang to "restrain Japan."

Still, no one at the Pentagon denies that China’s military has made huge leaps in the past decade. China now spends more on its military than any country except the United States, and will increase military spending to $148 billion this year from $139 billion in 2013, according to IHS Jane’s, a military industry consulting and analysis company. While that is still only about a fourth of what the United States spends, U.S. military spending is declining, to $575 billion this year from $664 billion in 2012. By next year, analysts estimate that China will spend more on its military than Britain, Germany and France combined.

Moreover, for Beijing, the Liaoning is a launching pad for future naval operations, military experts said.

"Back in August 2011, when the carrier later to be known as the Liaoning took its first test voyage, I happened to be aboard the USS John C. Stennis witnessing flight operations," said Andrew Scobell, a senior political scientist at the RAND Corp., referring to one of the U.S. Navy’s nuclear-powered aircraft carriers. "I recall shaking my head in amazement and thinking to myself, ‘The Chinese will never be able to do this!’"

But now, planes are taking off from the Liaoning. "The PLA is seen as extremely capable," Scobell said, "and one of the clearest indications of this is that the Pentagon now focuses considerable attention on countering what it dubs China’s ‘anti-access/area denial capabilities’" — military jargon for the doctrine that could be used by Beijing to deny the U.S. military the ability to operate in certain areas of the sea near China during a crisis.

Helene Cooper, New York Times

© 2014 The New York Times Company