WASHINGTON — In 1983, based on intelligence information, the United States handed the Soviet Union a diplomatic note objecting to nuclear assistance the Soviets were about to provide to North Korea. The Soviets, replying that they had not recognized that a potential for weapons development was involved, withheld or modified the aid sufficiently to satisfy Washington.
In 1977, when the Soviets shared with the United States intelligence that strongly indicated that South Africa was preparing to set off a nuclear device in the Kalahari Desert, pressure from the United States and other Western nations forced cancellation of the test.
The two incidents dramatize striking behind-the-scenes cooperation by the superpowers to prevent the spread of nuclear weapons--an "astonishingly successful" effort, according to Under Secretary of Defense Fred C. Ikle, one of the Administration's most hard-line officials.
Still, as the world prepares this summer to mark the 40th anniversary of the dropping of the first atomic bomb on Hiroshima, several incidents--including diversion to Israel and Pakistan of "triggers" that could be used for nuclear bombs, and secret plutonium experiments by Sweden--have reminded the world that the club of nuclear nations could grow again.
And beyond concerns about nations, there is a continuing threat that terrorists will "go nuclear"--a possibility that will continue to grow as nuclear technology becomes ever more accessible and weapons are further miniaturized. Already, the U.S. nuclear arsenal includes a 58-pound back-pack bomb.
Only six nations--the two superpowers, Britain, France, China and India--are known to have exploded nuclear devices so far, and it has been 11 years since India became the newest member of the nuclear club. That record stands in sharp contrast to the dark predictions early in the presidency of John F. Kennedy that 25 nations would have the bomb in 25 years.
A lot of the credit is attributed to superpower cooperation. In addition to information exchanges at twice-yearly meetings, the United States and the Soviet Union closely monitor the Nuclear Non-Proliferation Treaty, signed by them in 1968 and now ratified by a total of 129 nations. And the International Atomic Energy Agency (IAEA) enforces non-proliferation treaty safeguards to prevent diversion of uranium and plutonium from peaceful purposes to weapons.
The non-proliferation treaty "is the most widely adhered-to arms control treaty in history," according to Richard T. Kennedy, the Administration's ambassador-at-large on this issue. No nation that has adhered to it has withdrawn from it or, so far as is known, violated it, he said.
In fact, it is just about the only arms control agreement the United States has not accused the Soviets of violating. Even the breakdown of the arms control talks in Geneva at the end of 1983 did not interfere with a meeting between the two nations early the next year in their determination to prevent spread of the weapons.
Despite this remarkable record, "extraordinary vigilance, extraordinary effort, and extraordinary cooperation" will be required to maintain it, Kennedy said in an interview.
These are some of the clouds on the horizon:
--Several incidents of clandestine nuclear activity have abruptly surfaced, suggesting that the level of illegal dealing is higher than had been previously believed, according to Leonard S. Spector of the Carnegie Endowment for International Peace. Israel and Pakistan illegally obtained U.S-manufactured krytron triggering devices, for example, and Sweden conducted secret experiments in compressing plutonium toward a critical mass, one step short of full-scale atomic tests.
And South Africa has quietly hired American reactor operators in apparent violation of a U.S. law that, because of South Africa's nuclear activities, also bars U.S. uranium fuel for its electric power reactors.
--Non-nuclear nations are certain to complain that Washington and Moscow have collaborated to prevent the spread of weapons to the Third World at the same time that they have failed to reduce their own enormous nuclear arsenals, despite their commitment under the treaty to conduct "good faith" negotiations to end the arms race. The complaints are expected to surface at the third review conference of the non-proliferation treaty in Geneva in late summer.
The non-nuclear countries protest that the nuclear nations have used funds to prevent proliferation that should have gone to spreading peaceful uses of nuclear technology in less developed nations.