Military exchanges between China and the U.S. remain frozen despite a seemingly cordial telephone conversation between President Obama and Chinese President Hu Jintao and the forthcoming port call in Hong Kong of the U.S. aircraft carrier USS John C. Stennis.

Said a U.S. officer: "It's still a work in progress."

Indeed, China underscored its displeasure with the U.S. with not-so-subtle warnings last week. Two generals signed an essay lauding the increased capability of China's nuclear forces, including long-range missiles that could strike the U.S.

And a defense scholar asserted that China's white paper on military forces issued last month marked the limit to which China was willing to disclose military information.

The U.S., under several administrations, has sought exchanges with Chinese military leaders to persuade them not to miscalculate U.S. capabilities and intentions. This was forcefully expressed in public in 1999 by Adm. Dennis Blair, then head of the Pacific Command and now director of national intelligence. He told Congress the message to China was that the U.S. did not intend to "contain" China but "don't mess with us."

More recently, officials of the Bush and Obama administrations have urged the Chinese to be more "transparent" in strategy, budgets and procurement of weapons. Said Adm. Timothy Keating, the current Pacific commander: "We'd like a little more transparency in their long-range intentions." The commentary by Chinese scholar Chen Zhou, of the Academy of Military Science, sought to rebut that.

The present standoff began in October when the Bush administration and the government in Taiwan, the self-governing island that China claims, agreed on a $6.5 billion sale of arms to Taipei. The sale, if consummated, would include 330 Patriot anti-missile missiles intended to deter China from launching the 1,400 missiles it has aimed at Taiwan.

The Chinese immediately protested the arms sale and, as they have in the past when the U.S. displeased them, cut off port visits, exchanges of military students, and reciprocal visits by military leaders.

A Foreign Ministry spokesman, Qin Gang, said, "The United States ignored China's serious stance and strong opposition, and is bent on selling weapons to Taiwan, which has contaminated the positive atmosphere for U.S.-China relations."

Obama telephoned Hu several days ago but, so far as could be determined from the public record, did not discuss the estranged military relations between the U.S. and China except in convoluted terms. Xinhua, Beijing's official news agency, reported that Hu said "the core interest of either country should be respected by each other and taken into consideration."

Since the phrase "core interest" often refers to the Taiwan issue, in which the Chinese insist the U.S. should not interfere, that may have been the closest the two leaders came to the cause of the breakdown in military exchanges. Most of their conversation appears to have centered on the economic crisis.

U.S. officers insisted that the port call to Hong Kong later this month of the aircraft carrier Stennis, a 97,000-ton warship carrying 85 combat aircraft, would not reflect a revival of military exchanges. Evidently Chinese military leaders do not consider a visit to Hong Kong, the former British colony that was handed over to China in 1997, the equivalent of a similar visit to Shanghai or other ports.

Underscoring the standoff was the essay on nuclear weapons by Gen. Jingo Zhiyuan, commander of China's nuclear missile force, and Gen. Peng Xiaofeng, the political commissar of the force. They asserted that their force had strengthened "strategic deterrence" by being better able to mount intercontinental missile strikes and by creating a versatile missile inventory.

The two generals, breaking China's usual secrecy about its nuclear forces, said in an authoritative Communist Party journal that the Second Artillery, China's nuclear force, had expanded over the last three decades to combine nuclear and conventional missiles. They reiterated, Xinhua said, the "resolve of China to maintain its territorial integrity and guard national security."

In a related commentary carried by Xinhua, Chen, the scholar, contended that China's white papers on national defense have always focused on peaceful development and the pursuit of defensive policies in national security. He argued that the white papers have become increasingly open but have reached their limit.

Richard Halloran, formerly with The New York Times as a foreign correspondent in Asia and military correspondent in Washington, is a freelance writer in Honolulu.