Russia's nuclear arsenal is safe and militants could never steal an atomic bomb from the country, Defence Minister Sergei Ivanov was quoted as saying on Tuesday.
Russia has pledged to slash its numbers of nuclear warheads by about two-thirds from current levels of around 6,000 in a decade, but many experts fear militants might still be able to seize some from storage sites in the former Soviet Union.
"Unfortunately, in different regions of the world the myth is propagated that Russian nuclear weapons are guarded badly and weakly. This is a myth," Ivanov was quoted by Interfax news agency as saying.
"We give this question the highest priority because Russia understands its responsibility to protect nuclear weapons and to prevent possible accidents."
The deterrent value of Russia's nuclear weapons, built up during its Cold War stand-off with the United States, remains the foundation of its defence policy.
Since the end of the Cold War, Washington has made the prevention of nuclear terrorism a top priority, helping Russia to safeguard nuclear sites and stepping up surveillance to catch governments or individuals suspected of nuclear proliferation.
In contrast to its nuclear potential, Russia's conventional forces remain under-funded and demoralised after more than a decade of stop-start reform aimed at creating a force capable of dealing with modern threats.
Ivanov said all Russian nuclear weapons were accounted for and that no militants had come close to stealing one. "Never in the history of the Soviet Union or Russia have there been genuine attempts to steal nuclear weapons. And there have been no attempted terrorist attacks on nuclear installations."