The collapse of the Soviet Union has been messy and painful, but as long as anarchy is averted its far-flung nuclear arsenal probably will threaten no one, experts say. On the eve of the Ukrainian vote, however, Soviet President Mikhail Gorbachev warned that a breakup of the union could lead to economic chaos and a civil war involving nuclear weapons. “This could be a catastrophe for all mankind,” he said. By rejecting the union, Ukrainians inflicted a catastrophe on Gorbachev himself; he has become so irrelevant to Soviet affairs that his departure might cause more consternation in Washington than at home. But if the collapse becomes a more general disaster, if it leads to something like anarchy, Soviet nuclear weapons could indeed be used on their own people-or seep onto the global black market, where they might be turned against anyone.

The nuclear problem is at the top of the agenda for Secretary of State James Baker’s visit to Russia, Ukraine and Belorussia next week. The Soviet Union has about 27,000 nuclear weapons. Of that total, about 12,000 long-range weapons are based in only four of the original republics: Russia, Belorussia, Kazakhstan and Ukraine. The Soviet command-and-control system for strategic missiles is even more rigorous than the security system used by the United States. Shorter-range tactical weapons are more likely to become loose nukes. The Soviet arsenal contains about 15,000 of them, including missiles, bombs, mines and artillery shells. These weapons are more portable than strategic missiles and are subject to far less elaborate controls, Soviet and Western sources say. Until last year, short-range nuclear weapons were deployed in all 15 republics (map). They have since been withdrawn from the newly independent Baltic States and some other republics, but tactical nukes are still more widespread than strategic weapons.

Although Ukraine insists that it does not want to be a nuclear power, it’s not about to hand the weapons over to Gorbachev. Boris Yeltsin’s Russian Republic is rapidly absorbing the functions of the central government, and none of the other republics wants Russia to have a monopoly on nuclear arms. The weapons stored elsewhere have become bargaining chips to be used in negotiations between Russia and the other republics, or between newly independent republics and potential aid donors overseas. Already the Ukrainians seem to be reaching an understanding with the Kremlin. Bruce Blair, a Brookings Institution expert on Soviet command and control, says the two parties have agreed in principle to install “electronic blocking devices” that will prevent Moscow from launching strategic missiles based in Ukraine without approval from Kravchuk’s government. “The Ukraine will get a physical veto,” says Blair.

Under the new Strategic Arms Reduction Treaty (START), Washington and Moscow are supposed to destroy some of their long-range weapons. And Presidents Bush and Gorbachev have promised to withdraw and dismantle many tactical nukes. But a weakened Soviet government cannot carry out such tasks promptly. Sergei Rogov, a Soviet arms-control expert, estimates it would take at least 25 to 30 years to dismantle all of the weaponry. The U.S. Congress has voted $400 million for technological assistance, and Viktor Mikhailov, a Soviet deputy minister of atomic power and industry, says Moscow needs even more help. “We have a fantastic chance to destroy weapons right now,” he says, “but we must do it together.”

It could be a race against disaster. If the Soviet Union dissolves into chaos, tactical nuclear weapons could be fired, accidentally or otherwise. Nuclear missiles, warheads, components or materials might be sold on the black market. “You can picture a situation,” says Andrei Kortunov, another Soviet arms-control analyst, “in which the nuclear forces just melt–morale is down, people defect, computers malfunction, there’s no checking, there are accidents, blunders and so on.” He warns that “this scenario could happen even next spring.” Some of the approximately 10,000 Soviet nuclear scientists, who earn as little as 400 rubles a month ($4 at an exchange rate set last week), might hire out overseas. “People will accept offers from Saddam, Kaddafi, Iran,” says Rogov.

Bush has suggested that Soviet nuclear weapons be moved from the republics to the center for disposal. A recent report by experts at Harvard’s Kennedy School of Government says it would be faster to disable weapons on site. Ashton Carter, a coauthor of the study, outlines a program for “quick and dirty” disarmament. One step is to remove fissile material from warheads. “Wrap the pieces in plastic or metal wrap and squash them,” he says. The idea is to deform the material’s “geometry,” or physical shape, which prevents an explosion. Then, says Carter, “wrap the fissile material in very thick plastic and put it back into the bunker.” Such steps can be taken, however, only if republics like Ukraine agree to cooperate.

To encourage the elimination of Soviet strategic weapons by whoever controls them, Washington is considering new cuts in its own long-range arsenal, beyond those required by START. That, plus a new command system that includes a launch veto, might persuade the non-Russian republics to part with their strategic weapons. Increased food aid and financial support from abroad also could prevent misuse of nuclear weapons by helping to avert chaos. Congress has resisted such assistance; it recently rejected an attempt to divert $1 billion from the U.S. defense budget to economic aid for Moscow. But the nuclear problem cannot be separated from the Soviet Union’s other difficulties. The threat that the country could slide into nuclear-armed anarchy is a good argument for taking additional steps to stave off complete economic and social collapse.

Photo: (SYGMA)

Photo: Arms patrol: Destroying SS-20 missiles, a tactical nuke in Kazakhstan (VLADIMIR SUMOVSKY)

Map: (FRANK O’CONNELL)

How Many Fingers on the Button? Before the collapse of communism, nuclear weapons were stored in every republic. This year, they have been removed from some. Below, 1990 figures. Republic Number of Warheads ESTONIA 270 LATVIA 185 LITHUANIA 325 BELORUSSIA 1,250 MOLDOVA 90 UKRAINE 4,000 GEORGIA 320 ARMENIA 200 AZERBAIJAN 300 TURKMENIA 125 UZBEKISTAN 105 TAJIKSTAN 75 KYRGYZSTAN 75 KAZAKHSTAN 1,800 RUSSIA 19,000 KEY TO NUCLEAR SITES: Missle-launching bases; Bomber bases; Submarine ports; Weapon reactors; Uranium-processing plants; Design labs; Test site; Warhead stockpile concentrations SOURCE: NATURAL RESOURCES DEFENSE COUNCIL; U.S. DEPARTMENT OF DEFENSE