Soviets Said to Be Deploying World’s 1st Rail-Mobile Missile

WASHINGTON —  The Soviet Union is believed to have started deploying the world’s first strategic nuclear missile able to be launched from railroad cars, U.S. officials said Friday.

The new rail-mobile missile, known to Western analysts as the SS-X-24, can be moved on vast portions of the Soviet rail system to elude U.S. monitoring and attack, officials said, potentially complicating future efforts to verify Soviet compliance with arms control treaty limitations.

Deployment of the missile on rail cars has long been expected by the U.S. intelligence community, and senior Reagan Administration officials have attacked it as a potentially destabilizing development in the arms race.

U.S. confirmation of the deployment came Friday afternoon in response to a statement on the Senate floor by Sen. Jesse Helms (R-N.C.), alleging that the Soviets had violated a key provision of the unratified second strategic arms limitation treaty by deploying the missiles.

U.S. officials said the White House distributed a directive suggesting that reporters be told the Helms allegation was “essentially correct,” and that the deployment should be regarded as a “sobering” development.

A knowledgeable U.S. official said that while some U.S. intelligence experts dispute the allegation, “the preponderance of the intelligence community believes that the Soviet Union has begun deploying the rail-mobile SS-24.”

The SS-X-24, in development more than a decade, can carry up to 10 independently targeted nuclear warheads, the Pentagon says. Its range of 6,200 miles enables it to reach all major U.S. military targets via polar trajectories.