CHINA'S underground test on Oct. 5 ended a year-long hiatus on nuclear tests among the five declared nuclear powers.
Beijing's action is unfortunate. However, the remaining four - the United States, Britain, France, and Russia - should resist pressure to use China's test as a reason to resume their own. To do so, particularly for the US and Russia, not only would undercut the credibility of efforts to seek an indefinite extension of the Nuclear Non-Proliferation Treaty when it comes up for review in 1995; it also would undercut the credibility of the five nuclear powers' effort to negotiate a comprehensive test ban treaty (CTB) by 1996.
The year-long halt on testing - to which China never agreed - took firm hold last October when President Bush signed a bill amended to ban US tests through July 1, 1993. President Clinton extended the US moratorium to September 1994. Because Britain tests at Yucca Flats, Nevada, the amendment brought Britain's tests to a halt. Russia and France also had adopted moratoriums. All were contingent on no other country testing.
Now, pressure to start testing already is evident. A spokesman for the British Foreign Office was quoted as saying the test was ``regrettable'' but that ``we don't think that short-term testing is incompatible with a long-term comprehensive test ban.'' After the Oct. 5 test, Mr. Clinton called on China to join the other four declared nuclear powers in their moratorium on tests. Simultaneously, he asked the US Department of Energy to prepare for a possible resumption of tests at its Yucca Flats facility.
The leader facing the greatest pressure to test, however, could be Russia's Boris Yeltsin. The Russian military was unhappy about the mora- torium; he owes his success in ousting hardliners from the parliament building in Moscow to the military.
China's test, however, has little or no real bearing on the deterrent capabilities either in the West or in Russia. Indeed, it may only isolate China on nuclear issues. In commenting on its test, Beijing noted that the countries with the largest nuclear arsenals have a special responsibility to take the lead in cutting them. Although ratification is incomplete, the US and Russia have taken significant steps in that direction through the START I and II agreements. Beijing still insists that it supports efforts to negotiate a CTB by 1996. It should show that commitment by suspending further tests.