China's top arms control official assailed the United States today for its campaign to develop a shield against ballistic nuclear missiles, warning that such a program could lead to a nuclear arms race and dangerously alter the strategic balance in Asia and the rest of the world.

Sha Zukang, the Foreign Ministry's arms control director, also lambasted the Senate for its failure to ratify the Comprehensive Test Ban Treaty last month, arguing that such an act could make countries like China reluctant to enter into arms control agreements with the United States.

"Because I'm a negotiator I ask myself, 'What should I do?' " Sha said in a rare, wide-ranging interview. "Should we follow the same practice? We know the United States is a superpower, but that does not give you super rights."

Sha's statements reflect China's deep unease with current American strategic thinking, specifically the push to amend or even abrogate the 1972 Anti-Ballistic Missile Treaty. Underlying Sha's comments is a perception, shared by some European officials, that Washington is capitalizing on its status as the world's most powerful country to lock in a strategic advantage that would make it immune to intimidation.

The U.S. plan to create a shield against missiles would affect China because it would trump Beijing's single strategic ace. China's armed forces are still decades behind the American military. Its missiles, however, are top-notch and are the part of its arsenal that give it hope of becoming a world, or even regional, military power. "They are missile savants," said one Western military expert.

But creating an American national missile defense system would deny China the ability to threaten the United States with its nuclear warheads. That would severely skew the Asian security equation and leave China feeling trapped and powerless to pursue its interests, non-American Western diplomats say.

"Any amendment, or abolishing of the treaty, will lead to disastrous consequences," Sha warned. "This will bring a halt to nuclear disarmament now between the Russians and Americans, and in the future will halt multilateral disarmament as well."

Russia has already protested the American plan to modify the ABM treaty. On Nov. 3, Russia announced that it had tested a short-range interceptor rocket for the Moscow anti-ballistic missile system in what appeared to be a blunt warning about its own plans for an expanded ABM system. Western diplomats predict that an enhanced American missile shield will result in even closer security ties between Moscow and Beijing. Russia already sells about $1 billion of weapons a year to China.

In addition, some diplomats warn that a tough line from Washington on missile defense could prompt China to relax its new controls on nuclear proliferation and allow Chinese companies to resume selling nuclear weapons-related technology. And Sha said it would also threaten U.S. plans to bring China into the Missile Technology Control Regime, an international agreement that would place restrictions on China's sales of missiles and missile-related technology.

The American missile defense question is just one of several issues that have increased China's wariness of late. The May 7 NATO bombing of the Chinese embassy in Belgrade and allegations of Chinese espionage in the United States have roiled Beijing's ties with Washington.

Over the summer, the Communist Party is believed to have increased China's defense budget substantially. President Jiang Zemin met this week with officers from the armaments department of the People's Liberation Army and promised them more resources. The commander of China's air force, meanwhile, said his forces were planning to change their focus from a territorial defense force to one capable of attacking beyond China's borders.

Sha's comments revealed a significant shift in China's views about American plans for a missile defense system. In March, a senior Chinese official spent three hours warning a group of Western reporters that the most dangerous aspect of the U.S. campaign would be any moves to sell missile-defense technology to Taiwan, which China views as a renegade province.

Today, Sha did not mention Taiwan and instead focused on how the U.S. move threatened to skew the global strategic balance.

"It's the national missile defense that's really the most important," Sha said. "We are not rejecting the concept of missile defense completely, such as air defense to protect troops. But it is the advanced systems, in space and elsewhere, that are the problem. These are a violation of the ABM treaty. These may disturb or destroy the strategic balance."

Signed in 1972, the Anti-Ballistic Missile Treaty was one of the building blocks of the Cold War security system. Basically, it said that the Soviet Union and the United States would agree to forgo the development of weapons that could block a nuclear missile attack. The treaty was one of the main pillars of the strategic concept of mutual assured destruction, which said that the use of nuclear weapons by one side would immediately trigger a massive response by the other.

Washington has justified its interest in a missile defense system by saying it would not be targeted at any traditional power but rather at "rogue states" such as North Korea and Iraq.

Sha said this was difficult to accept. It is ironic, he contended, that the "United States . . . has been teaching the international community that the ABM treaty, though bilateral, is a cornerstone for strategic stability, that it's a precondition for further nuclear disarmament. Now suddenly they are attempting to amend it and threaten to abolish it. We have no words for this. Should we assume that the United States monopolizes all the truth in the world? This cannot be the case, I believe. So this will erode U.S. authority and credibility."

"Does this mean," Sha continued, "that the United States will negotiate treaties only for others, that the United States will expect others to honor all treaty obligations while the United States is free to do anything it wants? . . . Psychologically, that's bad for any new negotiations."

Sha said China is particularly worried that U.S. researchers have begun working with Japan to develop a missile defense system for U.S. allies in Asia. Chinese officials are alarmed by closer defense ties between Tokyo and Washington, which they see as part of a string of American defense relations--with South Korea, the Philippines, Singapore, Australia and New Zealand, and now Kazakhstan and even Mongolia--that are designed to surround China.

Sha also condemned the Senate's failure to ratify the Comprehensive Test Ban Treaty. He said neither of the Senate's two main arguments--that verification measures were weak and that the United States still needed to test its nuclear warheads--were persuasive. The United States has conducted more than 1,000 tests, he noted, greater by far than any other nuclear power; China has conducted fewer than 50. If the Americans say they need more tests, "other nuclear countries should have even more reason to have more tests," he said.

As for the verification issue, Sha was blunt. "As the chief negotiator for China, I would say this is an insult to the intelligence and capabilities of all negotiators who worked so diligently day in and day out and for so long on the treaty. I would strongly advise those guys to read the treaty, particularly the verification protocol, before jumping to such a conclusion."

China, he added, plans to stick to the terms of the treaty and press for its early ratification by the National People's Congress.