The political leaders of Taiwan, both government and opposition, are in serious danger of misreading or ignoring the increasingly stiff warning signals coming from Washington.

In its bluntest form, the U.S. message is: Taiwan needs to do more to prepare for its own defense against a potential attack from China rather than rely largely on the United States for its security. If it doesn't, the United States may be less obligated to come to Taiwan's rescue.

Publicly, that caution has been delivered by officials of the American Institute in Taiwan, the quasi-official embassy in Taipei that functions in the absence of normal diplomatic relations, by the Heritage Foundation, a conservative research organization in Washington with ties to President Bush's administration, and by the American Enterprise Institute, a more centrist think tank.

Privately, U.S. officials said that advice had been delivered from Secretary of Defense Donald Rumsfeld, by retired senior U.S. military officers visiting Taiwan, and by U.S. colonels who slip into Taiwan in mufti so as not to offend China as they confer with Taiwanese officers.

Said one senior officer: "Some of the investments that Taiwan would like to make are not optimized for the defense of Taiwan."

This widening rift between Washington and Taiwan, over which China claims sovereignty, comes just as the president of China, Hu Jintao, prepares to visit Washington next month. He is expected to repeat, as all Chinese do, that the future of Taiwan is the most sensitive issue between China and the United States and will undoubtedly try to widen the gap between Washington and Taipei.

Although Hu has proclaimed that China seeks to take over Taiwan by peaceable means, his government has repeatedly threatened to use military force if Taiwan declares formal independence.

The main point of contention between Washington and Taipei is a package of weapons offered by the United States that includes eight diesel-electric submarines, six Patriot anti-missile batteries, 12 P-3C anti-submarine aircraft, and other items worth $15 billion to $18 billion.

The Bush administration presented that package in April 2001, but the proposal has languished in Taipei ever since. President Chen Shui-bian, who belongs to the Democratic Progressive Party or DPP, has urged the Legislature to approve funds for the purchase but the Legislature, controlled by the Nationalist Party better known as the Kuomintang or KMT, has refused.

The KMT, which the United States supported against the Communists on the mainland for decades, has contended that some of the weapons aren't needed or they are too expensive or they aren't modern enough. Underneath it all, the KMT appears to relish opposing President Chen and the DPP.

In addition, leaders of the KMT have sought to undercut President Chen by visiting Beijing, where they were received like potentates of old who had journeyed from the provinces to the capital to pay tribute to the emperor.

American officers point to a steady decline in Taiwan's military spending, reductions in conscription, and a failure to adhere to high standards of training and readiness. Command and control of joint operations was said to be particularly weak.

Lastly, recent polls have brought into question the will of the Taiwanese to resist political, economic and perhaps military domination by the mainland.

Even so, those same polls show that a large majority of the people of Taiwan prefer to stay separated from the mainland, even if that means remaining in a limbo where only 28 nations have formal diplomatic relations with Taipei.

Bush sought to set a firm policy on Taiwan shortly after he came into office in 2001, saying that the United States would do "whatever it takes" to defend Taiwan from the mainland. The arms package was intended to underscore that pledge.

After the terrorist assaults of Sept. 11, however, the administration toned down its rhetoric on Taiwan as it sought to enlist China in the war against terror. Further, the administration admonished President Chen to moderate his drive toward Taiwan's formal independence, the basic platform of his party.

Now, the pendulum has swung back a little as the Bush administration has pressed Taiwan to complete the purchase of the weapons it requested in 2001. A Pentagon report last month noted that the military balance between China and Taiwan "appears to be shifting toward Beijing as a result" of China's economic growth, diplomatic leverage and improved military capabilities.

The report concluded that China's military modernization "has increased the need for countermeasures that would enable Taiwan to avoid being quickly overwhelmed."

Richard Halloran is a Honolulu-based journalist and former New York Times correspondent in Asia.