Spy stories always thrive on grotesque stereotypes, and the allegation that US nuclear secrets were leaked to China by a Taiwanese-born scientist at the Los Alamos National Laboratory is no exception. Of course national security must be protected. But some press reports in the wake of unproven allegations have presented an unsavoury and unsubstantiated picture of the role of Chinese-American scientists in the United States. In this climate, it is imperative that the US scientific leadership spells out the extent to which US science is indebted to this group, and to the principle of free global exchange of information between scientists.

The People's Republic of China is today the largest source of scientific immigration to the United States, by a considerable margin. According to figures compiled last year by the National Science Foundation (NSF), China supplies well over one-third of the 8,000 foreigners who receive doctorates in the United States each year. Chiefly because of legislation which Congress passed in 1992, as a form of retaliation against the Chinese government for its treatment of student protesters in Tiananmen Square, the Chinese students are automatically entitled to stay in the United States. According to the NSF, 90% of them intend to do so.

The next largest group of immigrants comes from India — another country whose scientists some branches of the United States government are inclined to view with suspicion. This generation of young Asians represents a critical component of the future of US science. Most of these young scientists will become citizens of the United States. They will be just as committed to America as the smaller groups of European scientists who have flowed into the United States, in fits and starts, for most of the century.

The Asian influx comes at a time when, according to studies too numerous to mention, qualified American-born students are not prepared to enter doctoral studies in numbers sufficient to satisfy the demands of the US research universities. It is the overwhelming view of the academic and industrial experts that these immigrant scientists are filling slots that would otherwise go unfilled, and that their presence in the United States is of fundamental importance to the growth and development of science in the United States.

Ironically, in light of the reaction to the Los Alamos saga (see page 447), a US Commission on Maintaining US Nuclear Weapons Expertise has just reported that the weapons laboratories are already having trouble recruiting scientific staff. Like everyone else, these laboratories are going to have to hire where the talent is. But they are under increasing pressure from the Congress to subject recruits, as well as visitors, to ever more vigilant security checks. But the introduction of polygraph tests and other counter-intelligence procedures at the laboratories can only complicate the already considerable challenge they face in attracting staff. Any hint of a clamp-down on recruits with foreign backgrounds will further isolate the laboratories.

The greatest burden of any such clamp-down would fall, of course, on the Chinese-American scientists themselves. It is incumbent on the American Physical Society and other scientific societies to tell the public the truth about this matter. Chinese-American scientists play a large and increasing role in maintaining US science. These scientists are here at the express invitation of the US Congress; their presence is China's loss and America's gain.

More support should be forthcoming from national leaders in support of Chinese-Americans' role in science and society. President Bill Clinton is constrained, unfortunately, by the circumstances in which the Los Alamos leak — which actually occurred in 1988 — has sprung to prominence in Washington. Clinton and his Democratic Party have long been accused of taking money, through intermediaries, from the communist government of the People's Republic of China. The communists almost certainly did make such donations — after they realized that Taiwan had bought access to the Republican Party. Now the Republicans seek to exploit the Los Alamos leak to portray Clinton as soft on China. This is a puerile Washington mud-fight which nobody will win: the losers are likely to include the weapons laboratories, a hard-working and immensely talented immigrant group, and US science.