This document also available in PDF Image . In 1991, the Russian Federation inherited most of the Soviet Union's nuclear weapons, nuclear command and control system, and nuclear doctrine and employment strategy. It has altered both the nuclear doctrine and force structure in response to domestic economic pressures and its evolving position in the international environment. Russia has placed a greater reliance on nuclear weapons than did the Soviet Union, both as a measure of its superpower status and as a deterrent to a wide range of challenges and conflicts. Where the Soviet Union focussed on the prospects of a global conflict, Russia focuses more on emerging regional threats and challenges. And, although the Soviet Union stated that it would not use nuclear weapons first, it did plan to use these weapons early and offensively if a conflict occurred. Russia, in contrast, has stated that it would consider first use of nuclear weapons if its conventional forces were inadequate for its defense. This is worrisome because severe financial shortages have undermined the combat capabilities of Russia's conventional forces. Many in Russia believe that the threat to use nuclear weapons as a last resort will deter regional adversaries and protect Russia's national security interests. Russia has continued a process begun by the Soviet Union to reduce and consolidate its nuclear forces. It has removed all the former Soviet nuclear weapons from the non-Russian former Soviet republics and it has proceeded with the reductions mandated by the START I Treaty. Russia has continued to modernize its strategic nuclear forces, although at a slower rate than did the Soviet Union, by producing new single-warhead ICBMs, a new ballistic missile submarine, and new submarine launched ballistic missiles. It has also continued work on some Soviet-era underground defense facilities. Russia has also continued to exercise and test its strategic forces and troops. Russian officials claim that the results of these exercises demonstrate that Russia's nuclear forces remain potent and reliable. Nevertheless, sharp economic constraints have slowed Russia's modernization programs and raised questions about the future viability of Russia's nuclear forces. Numerous concerns have surfaced about the status and reliability of Russia's nuclear command and control system. The economic pressures on Russia's forces may increase the prospects for further negotiated reductions in strategic offensive forces. Russia would find it difficult to maintain its forces at START I levels for any length of time because many of its existing systems have neared the end of their service lives. But Russia might also find it difficult to keep its forces at START II levels, if that treaty enters into force, unless it keeps some of its missiles with multiple warheads. This would violate the terms of the treaty but would be far less costly than an effort to produce hundreds of new single-warhead ICBMs. On the other hand, if the United States and Russia agree to further reductions under a START III treaty, Russia could retire its older weapons systems and deploy a treaty-compliant force without producing large numbers of new missiles.