Even as the Pentagon is embarking on the biggest shipbuilding program since World War II, its weapons chiefs are closing in on a series of anti-ship devices that could doom surface ships in a war.

Satellites that could see through clouds would find the ships; long-range bombers would fly to the general area; anti-ship missiles far more deadly than those being used today around the Falklands would steer themselves right into the targets.

Although this might sound like some Pentagon planner's dream, the various parts of that combination are already in hand or close by, forcing a question upon decision makers: "Why let the Navy keep building billion-dollar ships that can be sunk by million-dollar missiles?"

Navy leaders are aware of the question, and apprehensive. But they want the ships, the costliest part of the huge rearmament program President Reagan has approved for the next several years.

The Pentagon already has done considerable paper work on a satellite with radar eyes that, regardless of the weather, could etch out the profiles of ships sailing the world's oceans. Some of the study was done under a project called Clipper Bow.

Although the ocean satellite is still on paper, Pentagon officials say there are no insurmountable technical obstacles. The Soviet Union already has a crude version of the ocean surveillance satellite. The Soviet version relies on radioisotopes to generate the power needed to send radar beams down to the ocean. Pentagon researchers believe they could do the job better with batteries charged by sunlight.

The bomber part of the anti-ship combination is in hand. The Air Force, with the full blessing of Pentagon civilians, is studying how to convert its B52G bombers into ship-killers. Even more lethal in the anti-ship role, according to defense officials, would be the radar-elusive B1 and Stealth bombers scheduled for duty in the late 1980s and early 1990s.

Air Force bombers have such a long range that they can reach the crucial sea lanes from even the comparatively few land bases the United States still has around the world. Gen. Lew Allen, Air Force chief of staff, has reportedly been complaining in Pentagon discussions that other nations are making better use of land-based aircraft for covering the sea lanes than is the United States.

His view is boosted in a secret draft guidance to the Air Force, issued over the name of Defense Secretary Caspar W. Weinberger, which calls for more emphasis on the anti-ship mission. Pentagon civilians are considering putting new engines in B52G bombers to give them even more range for patrolling the seas.

"Smart" missiles that can guide themselves into ships after being launched from aircraft are a reality, as dramatized by the French-made Exocet missile that ruined the British destroyer Sheffield after being fired from an Argentine plane in the battle over the Falkland Islands. The United States, according to the Pentagon, has missiles in development that are better than the Exocet.

One portrayed that way is the anti-ship version of the Tomahawk cruise missile, the MRASM, for medium range anti-ship missile. A B52 could carry more than a dozen MRASMs and fire them while still more than 100 miles away from the ship. The MRASM, once in the area, would home in on the heat generated by the ship and strike with a 500-pound bomb.

All this potential for sinking surface ships is not good news for everybody in the Pentagon, however.

Navy leaders are well aware that they will be confronted with the question of the potential vulnerability of their expensive new ships every time any element of the anti-ship combination dramatizes its worth, as was the case with the Exocet fired against the Sheffield. And the restructuring of traditional roles seems to be under way already by order of top Pentagon civilians, although none of them wishes to portray the new anti-ship weapons initiatives that way.

Richard D. DeLauer, undersecretary of defense for research and engineering, said his office is exploring how to exploit the potential of "all weather" satellites, Air Force bombers and anti-ship missiles for defending the U.S. fleet and attacking the Soviet fleet in wartime.

"There's a tentative program for some of the B52s in the maritime support role," said DeLauer in an interview confirming that the Strategic Air Command's interest in getting deeper into the anti-ship mission is getting high-level attention. As B52G bombers are replaced by the new B1, starting in 1986, SAC and DeLauer see a job for them in helping to guard the sea lanes.

"I think it's great," said DeLauer of an anti-ship role for the B52G. "It's got legs."

Although not willing to go along with those who say offensive weapons for sea warfare have gotten so far ahead of defensive weapons that surface ships may be doomed, DeLauer said: "Survivability is a problem. There are two things that we should be looking at in all our systems: survivability and endurance. The surface fleet is terrific for force projection. But you want to be sure you get it survivable."

Navy leaders, while expressing confidence in their ability to defend aircraft carriers and other warships against smart missiles, have said for years that Soviet Backfire bombers armed with cruise missiles pose grave threats to free world shipping. The Pentagon is stepping up its efforts to pose the same kind of threat to the Soviets as part of the rethinking on how best to prevail at sea.