Both the United States and the Soviet Union are developing weapons specifically designed to destroy the other's land-based missiles in a surprise strike, Pentagon officials acknowledged yesterday.

Critics contend that such a "counterforce" capability, pursued by the United States in the 1950s and abandoned in the 1960s when the Soviet Union put its missiles underground, will make the balance of terror between the two superpowers more precarious.

Backers, including Defense Secretary Harold Brown, counter that it would be more dangerous for the United States to leave the field of counterforce weapons to the Soviet Union. The United States must respond in kind, Brown argues.

President Carter is expected to decide soon which of two counterforce missiles - ones with enough explosive power and accuracy to destroy Soviet land missiles despite the tons of concrete protecting them - to put into production.

A high-ranked Pentagon executive acknowledged yesterday that either of the two missile options - the Air Force's MX blockbuster, under development, or the so-called "common missile," made up of parts from the MX and the Navy Trident missile - could destroy Soviet intercontinental ballistic missiles (ICMBs) buried in underground silos.

Once either MX or the common missiles were deployed, defense officials conceded, the United States would be threatening Soviet ICBMs to a greater degree than at any time since the late 1950s and early 1960s when Soviet land missiles were above ground and thus very vulnerable to destruction.

Arms controllers warn that if the United States and the Soviet Union have lots of counterforce weapons pointed at each other, the temptation will be to launch ICBMs at the first sign of an attack rather than risk losing them. Such a launch-on-warning policy, they contend, could trigger nuclear war in response to a false alarm.

But at the same time the Pentagon is spending billions of dollars to make the U.S. nuclear arsenal accurate and powerful enough to knock out Soviet ICBMs, it is searching for ways to keep Russia from doing the same thing to the United States. If this search is successful, Pentagon leaders contend, the United States could ride out a first strike and fire back only in retaliation.

"We and the Soviet Union are reaching a period in which each can successfully target the other's hardened fixed systems more cheaply than either can further harden its systems to make them survive," Brown said in portraying the current dilemma Wednesday to the graduating class of the U.S. Naval Academy.

Rather than pour more concrete on top of the silos holding land missiles in a futile effort to protect them from new counterforce weapons, Brown explained, both the United States and the Soviet Union are being driven into making their land missiles mobile so they will be harder to hit and destroy.

But Carter, as part of his deep personal involvement in this search for a less vulnerable land missile, has been warning Pentagon leaders against schemes which could come back to haunt the United States if theSoviets were to adopt them. The president believes the Air Force proposal to hide about 200 MX missiles in a field of 4,000 identical holes falls into his category. If the Soviets dug 4,000 holes of their own and said only 200 missiles were being circulated among them, how could the United States be sure this was so? This has proved to be a sticker, Pentagon officials said yesterday.

After sifting through the various missile options in meetings with Carter and answering this long list of questions written in the margins of top-secret Pentagon reports, top defense officials believe only two schemes have passed muster.

The first one, defense officials said yesterday in giving the most detailed rundown yet, would put 200 MX missiles on railroad cars and pull them along stretches of track from 15 to 20 miles long on government land in the Southwest.

The tracks would be laid at the bottom of ditches covered with removable roofs of concrete and dirt. A locomotive would pull the MX railroad car from one concrete "station" to another. The stations would be about 3,000 feet apart.

Only the 8,000 concrete stations hiding the MX would be fenced off from campers, hunters and cattle to avoid putting an unacceptably large amount of land off-limits to the public.

The roofs on both the ditch and the stations would be removed about once a year to enable Soviet satellites to verify how many missiles were hiding along the railroad tracks.

Besides 200 MX missiles on rails, this first option calls for deploying 3,000 cruise missiles on airplanes built expressly for them. Each cruise missile would carry a warhead of 150 kilotons that would be designed to land within 200 feet of its target.

Also, under this option, 20 Trident submarines, each armed with 24 Trident I missiles, would patrol the Atlantic and the Pacific.

The second option would give up on the idea of trying to make land missile mobile so they would be harder to hit than today's force of 1,054 ICBMs standing still in underground silos. Option two calls for putting new counterforce missiles in 400 of the existing 550 Minuteman III silos and stationing other counterforce missiles at sea in Trident submarines.

The counterforce weapon for the second option would be the smaller common missile made from the MX and Trident I missiles. Although not big enough to carry the MX load of 10 warheads of 335 kilotons each, defense officials said, this common missile would be accurate and powerful enough to destroy Soviet land missiles.

In addition to putting 400 common missiles in Minuteman III silos, 480 more would be deployed on 20 Trident submarines.

To further hedge the bet, 5,000 cruise missiles would be deployed on 175 of the special planes built to withstand the electromagnetic effects of nuclear explosions.

Defense officials said yesterday that the second option would make the air and sea legs of the nuclear triad so strong that attacking the third one, land missiles, "would be an act of insanity."

Option one and option two, they said, each would cost $70 billion to build over 10 years. It would take until 1986, they added, to build and deploy the new counterforce missiles.

Brown said the Soviets have been trying since 1962 or 1963 to develop missiles deadly enough to knock out U.S. land missiles. With their new SS18 and SS19 missiles, he said, they will soon have that capability.

In a separate development, the House yesterday rejected attempts to delete language from the Pentagon's fiscal 1979 supplemental money bill that would direct the Carter administration to proceed concurrently with the MX missile and its basing system.