In Washington, officials are worried that the breakup of the Soviet Union may create an entirely new kind of global nuclear threat. “It’s terrifying what might happen,” a Pentagon analyst told NEWSWEEK. “The dimensions of this problem are beginning to sink in with us.” Both the White House and Congress appear uneasy. With Gorbachev’s advisers wondering out loud about the Soviet Union’s ability to control its own nuclear arms, Bush last week demanded that their safety be “totally guaranteed…The last thing the world needs is some kind of nuclear scare.” House Armed Services Committee chairman Les Aspin proposed transferring $1 billion from the Pentagon budget to the Soviet Union for food and medical relief.

For now, the chances of a Soviet ICBM being launched at the United States-or of Muammar Kaddafi buying one-seem remote. During the coup, in fact, the only actions the Soviet military took with its strategic arsenal were reassuring ones for Washington. The Pentagon learned that the Soviet Union lowered the alert status of some of its strategic nuclear weapons capable of striking the United States. The Soviet military also scaled back the flying hours for long-range bombers. Chief of the Soviet Strategic Rocket Forces Gen. Yuri Maksimov, an opponent of the coup, took the unprecedented step of ordering SS-24 missiles, positioned on rail cars, and mobile SS-25 missiles back to their garrisons. U.S. intelligence sources tell NEWSWEEK those missiles remain warehoused.

Even more encouraging are signs that the breakaway republics have little interest in maintaining nuclear arms on their soil. About 80 percent of the estimated 12,300 offensive strategic warheads and 12,200 tactical warheads are located in the Russian Republic; the rest are scattered in the Ukraine, Belorussia and Kazakhstan and eastern Germany. Ukrainian and Belorussian leaders have said they want their republics to be nuclear-free zones. Kazakhstan last week shut down its nuclear-weapons testing range in Semipalatinsk. And the Soviets have promised to remove all their tactical warheads from eastern Germany by 1994. Even with a breakup of the Soviet Union, U.S. officials believe that the republics would allow the central government in Moscow to manage the nuclear forces. The republics may add another layer of protective control by demanding veto authority over the use of any nuclear arms remaining on their soil.

But U.S. officials are more confident about the security of the Soviet ICBMs than they are about its tactical nuclear weapons. Though many of the latter pack more explosive power than the bomb the U.S. dropped on Hiroshima, these nukes are smaller, and thus easier to misplace or to steal, than the large strategic systems like bombers, ballistic-missile submarines and ICBMS. U.S. intelligence analysts do not believe that terrorists could penetrate the well-defended facilities that house the tactical warheads. “But warheads could disappear,” one senior U.S. official worries. In this scenario, the Soviet Army shrinks following disunion, the loyalties of soldiers are divided as republics compete for individual military units and corruption begins to infect the leadership. “The technical guys here know how easy it is to break some of these safeguards and controls,” says a Pentagon official. “The next thing you know one of these nukes ends up on the docks of Beirut.”

Or perhaps the scientist who built it. Bush administration experts believe the Soviet defense industry will be devastated by disunion and the inevitable dislocations caused by market reforms and potentially drastic cuts in military spending. Weapons plants and design bureaus will be shut down, throwing thousands of engineers and scientists out of work. If the KGB no longer operates its domestic spy network, it will not be able to prevent scientists from emigrating. Many of them could slip away like German rocket scientists did after World War II-and, says one administration analyst, “go to places we wouldn’t want them going to. " The Bush administration asked Moscow last week for assurances that its nuclear weapons and secrets remain in safe hands. In the current tumult, there are no guarantees.