The nation's highest-ranking military officer said yesterday that the United States must make its landbased missiles mobile to keep them from being distroyed by the thousands of Soviet nuclear weapons aimed at them.

"And," declared Air Force Gen. David C. Jones at his first news conference since becoming chairman of the Joint Chiefs of Staff, "to the Soviets I say, you have caused this problem by your large number of reentry vehicles with increased accuracy."

A reentry vehicle is an H-bomb shaped for gliding to earth to a target after being carried aloft by a missile. One missile can carry several reentry vehicles, called RVs.

The Soviets are deploying so many accurate reentry vehicles, according to Air Force leaders, that these RVs will soon be able to gang up on the U.S. force of 1,054 land-based missiles and cripple them before they could be launched from their underground silos.

"It is important to do something about that vulnerability," Jones said.

"I would have deep reservations" about any kind of new arms control agreement that did not allow the United States to make its land missiles less vulernable, he said.

"The most attractive" way to protect land missiles. Jones said, is to play a sort of "shell game" with them. One missile, complete with launcher, could be trucked around an extensive field of 20 different holes in such a way that the Soviets could never be sure which one held the missile.

By deploying 200 to 300 missile this way, the Soviets would have from 4,000 to 6,000 holes to cover with their reentry vehicles. Backers of this concept, call MAP (for multiple aim point), contend that the Soviets could not be sure of covering all the possibilities and thus would not launch an attack against the United States. Critics counter that MAP amounts to putting the cannon in the village square and inviting more nuclear firm on the American people.

MAP "looks cost-effective to us," Jones said, because the United States would be spending a lot less money digging holes than the Soviets would in building enough reentry vehicles to cover them all. The new JCS chairman said he envisions using both existing Minuteman land-based missiles and the blockbuster MX missile under development in the shell game.

Under the new strategic arms limitation talks (SALT) treaty being negotiated with the Soviets by the Carter administration, mobile missiles could not be deployed until 1981 but could be developed in the interim.

Jones said: "I consider the mobiles are authorized. And to me that is not a matter for discussion or negotiation."

Defense Secretary Harold Brown also has insisted that the United States should hold open the option of deploying mobile land missiles once the planned protocol banning them expires at the end of 1980.

This growing pressure for moving into mobile missiles is a departure from the government stance in 1972 when arms control negotiators tried to prohibit mobile missiles for fear they would destabilize the nuclear balance between the two superpowers.

In fielding other questions, the 57-year-old Jones made these points:

SALT Linkage - "It is very tempting in view of what the Soviets are doing in human rights and in Africa and other areas of the world," to call off the strategic arms limitation treaty talks, but limiting strategic weaponry "could be to the advantage of both sides . . . I also say we ought to hang tough on the negotiations." He added that he was encouraged "by our holding firm on some of the issues" in the SALT negotiations.

Defense Spending - The United States should spend more on strategic weapons in the future even if a new SALT treaty is signed. However, no agreement would require even higher defense spending. "I just want to dispell any idea that SALT is going to mean a reduction in the strategic force budget in the days ahead."

B1 Bomber - Jones said some persons he did not identify urged him to "end run" President Carter after the president canceled the B-1 bomber "any try to get Congress to appropriate and direct the money" be spent for the plane. "I refused to become involved."

Soviet Backfire Bomber - The chiefs have stuck to their position that the Soviet Backfire should be counted as a strategic weapon under any new SALT agreement. Jones denied that there has been any kind of a deal under which the chiefs would agree to let the Backfire go uncovered by the new SALT agreement in exchange for getting money for more air defense and a new bomber.