Defense Secretary Frank Carlucci bluntly accused the Soviet Union of producing nuclear arms designed for a first strike and challenged the Kremlin to reveal its military budget as proof of glasnost, or openness.

Carlucci made the comments Monday on the eve of an unprecedented visit Tuesday to the secret Kubinka Air Force Base near the capital to inspect the Blackjack bomber, Moscow's newest and most deadly long-range nuclear-capable bomber.Later, the defense secretary was to visit Red Army division headquarters at Tuman, also on the outskirts of Moscow, then hold another round of talks with his official host, Defense Minister Dmitri Yazov.

Both facilities have been strictly off limits to foreigners, and the Soviets hope that allowing a U.S. defense chief to inspect the facilities personally will convince Washington that even the super-secret Soviet military has been bitten by the glasnost bug.

Pentagon officials believe the Blackjack bomber, which first appeared in 1986, adds a new dimension to the Soviet ability to strike deep inside the U.S. heartland with nuclear weapons.

The aircraft is capable of launching AS-15 nuclear-tipped cruise missiles and also can conduct reconnaissance and strike operations in a nuclear war lasting beyond an initial missile exchange.

Carlucci's four-day visit to the Soviet Union is part of the continuing exchanges of military personnel designed to ease tensions between the superpowers and prevent incidents and accidents from escalating into dangerous conflict. Last month Marshal Sergei Akhromeyev visited military installations in the United States as part of the program.