The Defense Department is reviewing the test program of the president's Strategic Defense Initiative (SDI) to see what cost advantages and other benefits might result from a less restrictive reading of the 1972 Antiballistic Missile Treaty, according to testimony before a Senate subcommittee yesterday.

Until last year, the U.S. interpretation of the treaty was that it barred testing in space of so-called exotic or new-technology weapons such as lasers or particle beams designed to knock down incoming ballistic missiles.

A Defense Department review of the negotiating record, however, determined that research, development and testing of such weapons could take place in space and that the treaty barred only deployment of such systems.

An interagency battle developed over that approach, with several of those involved in the 1972 negotiations saying the new interpretation was incorrect.

Finally, President Reagan determined that the Defense Department view represented the legal situation but that the administration would continue to follow the traditional, more restrictive interpretation pressed by the State Department.

Under that approach, the SDI test program was planned in a way that would provide data on the feasibility of a system by the early 1990s. Findings would come from partial tests of components, computer simulations and war gaming, Lt. Gen. James A. Abrahamson, director of the SDI Organization, told the Armed Services subcommittee on strategic and theater nuclear forces.

Abrahamson said, however, that he had been given "a new opportunity" to review the test program and was "just beginning to examine" the programs to see how they would be handled under the less restrictive interpretation.

With no hindrance by the treaty, Abrahamson said, "we could go directly to the most convincing tests," which he said would also be the "most cost-effective."

"It could save both money and time and gain a higher confidence in results," he said.

He said the organization was hesitant to take a position on the controversial matter, saying that the restrictive approach was chosen "for good political reasons" and that any change would be "made above my pay grade."

Assistant Defense Secretary Richard N. Perle, who had pushed the broader testing interpretation, told the subcommittee that he does not "think we can make an intelligent decision" on whether to develop an SDI system "on the basis of the kind of testing permitted under the restricted" interpretation of the ABM treaty.

He said the sooner a change was made to unrestricted testing, "the greater the progress" on the SDI, also dubbed "Star Wars."

Abrahamson also said he was protecting an option of a "limited near-term deployment of a limited ABM capability" as a possible response if the Soviets deploy such an ABM system.

Perle reiterated an administration charge that the Soviets are moving toward such a step with their new large radar in central Siberia and other fixed and mobile radars around the country.

Perle also declared his view that if U.S. research develops a workable SDI system, "we would be well-advised to go ahead whether or not the Soviets agreed" to modify the ABM treaty.

In response to a question by Sen. Carl Levin (D-Mich.), Perle said his view on that was not the administration view. "I'm probably ahead of the administration," he said.

Perle also said he thinks that "we ought to devote more funds to defense and rather less to offensive strategic nuclear forces." He said it would "make no sense at all" to deploy the proposed Midgetman mobile missile with only one warhead.