THE end of the cold war, an abortive coup in Moscow, and the breakup of the Soviet empire changed the nature of the nuclear danger posed by Russia. The threat of a deliberate attack receded, while the danger of anarchy grew. Preventing a breakdown of control over nuclear weapons and materials seemed more urgent and much harder than containing Russian imperialism and deterring aggression. Despite bipartisan US efforts to shore up nuclear control in Russia and other former Soviet republics, that control remains shaky. We can take some comfort from the denuclearization of Kazakhstan and the ongoing removal of weapons from Ukraine. We can also take heart that Russia, with American assistance, is improving safeguards on fissile materials at some major facilities. But apprehension persists about the smuggling of nuclear weapons or fissile materials to rogue states or terrorists; the unauthorized use of nuclear weapons by rouge Russian units; the loss of legitimate and competent control at the top of the chain of command; and the launch of nuclear forces on false warning. Smuggling grabs the headlines, as specialists and the media declare this the biggest threat to US security today. Yet scant evidence of smuggling exists. Since 1991, Russia has temporarily lost control over small quantities of weapons-grade material in a few cases. The most sensational incident involved a sting operation hatched by German intelligence that created artificial demand for the stuff. In all cases, Russian or European security agencies seized the diverted material. The record does not faze some purveyors of doom: A recent issue of Business Week, for instance, asserts that ''contraband trade in weapons-grade nuclear material is thriving.'' The chorus crying wolf only distorts and discredits the reality that a serious risk of future leaks exists. The civilian nuclear institutes certainly have deficient safeguards, and custodianship has deteriorated across the board. Amateur crimes of opportunity as well as insider corruption remain a distinct risk at Atomic Energy and Defense Ministry sites. SUBSTANTIAL leakage of other sensitive dual-use technologies has already taken place. Lax enforcement of export controls continues to allow such technology to flow rather freely out of Russia, Ukraine, and Kazakhstan. Moreover, criminal conspiracies in this illegal trade have surfaced. In one foiled caper, criminals diverted beryllium from an institute that also housed a huge stockpile of weapons-grade nuclear materials. The risk of the unauthorized use of strategic forces by rogue commanders of the land-based rockets, submarine missiles, and bombers appears to be negligible today. Low-level commanders have little ability to do anything without permission from Moscow. Intercontinental rockets in silos have especially impressive safeguards. Any attempt by a local launch crew to pick the lock on their blocking devices would automatically be reported to the war room of the General Staff, which can electronically isolate the deviant launch center. Safeguards are weaker on submarines because of the crew's autonomy during long patrols at sea. A renegade crew might be able to circumvent the blocking devices. Even weaker safeguards are found on the bombs and cruise missiles for bombers, though to compensate, Russia keeps payloads separate from the aircraft and specially guarded. Although Russian safeguards compare favorably with US controls, they are just gimmicks designed to buy time. In the event of a serious security breach, Russia would have to dispatch troops to regain custody. Another ominous trend stems from the insistence of US arms negotiators that Russia shift the bulk of its strategic warheads out of better-safeguarded silo-based rockets into mobile rockets and submarines. At the top the nuclear chain of command, political turmoil spells trouble: fuzzy and tenuous nuclear authority susceptible to sudden shifts of allegiance that could shatter the coherence of control. Military subordination is precarious because President Yeltsin created no institutional replacement for the old Communist Party apparatus, instead relying on personal loyalties. The weak institutional base of his nuclear authority magnifies the fact that the Russian military, just like the US military, holds the codes necessary to launch a strategic attack. The 1991 coup attempt taught Russia that political turmoil mixed with distrust and alienation throughout the military high command severely strains the integrity of the nuclear command system. After the coup, some advocated assigning representatives of parliament to the General Staff war room to prevent any mishandling of the nuclear launch codes. But parliament lacked, and still lacks, the ability to impose checks and balance on nuclear decisionmaking. Mr. Yeltsin seeks to further concentrate warmaking power, including the right to use nuclear weapons. Turmoil at the top persists at a time when Russia feels more dependent than ever on nuclear weapons. The demise of the Red Army that formerly protected Russia shifted the burden of security onto nuclear forces. Russia's new military doctrine abandons its former pledge of no-first-use of nuclear arms, and widens the conditions under which it might use them. By increasing its reliance on these weapons, Russia also magnifies the significance of its nuclear strategy. The 1994 agreement between Russia and the US to stop aiming missiles at each other did not remove this hair trigger. Russian nuclear strategy still relies almost completely on launch-on-warning - that is, launching their strategic missiles after an enemy missile attack is detected but before the incoming enemy missiles arrive. This strategy is dangerous because it allows only three or four minutes for detecting an attack, and another three or four minutes for top-level decisionmaking. Russia not only regularly exercises its nuclear quick-draw, but evidently entered the early phases of the procedures in January, when a Norwegian scientific rocket triggered a false warning that activated Yeltsin's nuclear suitcase. This false alarm suggests another worrisome fact: Russia's early-warning network is falling on hard times like the rest of the military. Our security depends not only on preventing smuggling but also on Russia reducing its reliance on nuclear arms, and ending its practice of keeping a large portion of the arsenal on high alert. The world will remain insecure as long as thousands of launch-ready nuclear weapons remain at the fingertips of a nuclear command system tottering on the edge of civil collapse.