The Army has set up a special team to assess the damage it may have suffered as a result of the alleged spying by John A. Walker Jr. and his cohorts, Defense Department officials said yesterday, confirming fears that compromises of sensitive operations extend beyond the Navy.

For coding sensitive messages, the Army, Air Force and Marine Corps use equipment similar to the devices that the Navy believes were compromised to allow the Soviets to read its top-secret communications for years, sources said.

The Army damage-assessment team is working with the Navy's, which has been painstakingly listing secrets that the espionage ring was in position to give the Soviets. This two-service effort comes at a time when some U.S. officials are warning that the damage to national security by the alleged Walker ring may extend to sensitive intelligence activities as well as the operations of the entire U.S. military.

The prime area of concern, officials said, is what the Soviets learned from intercepting sensitive messages and breaking through their codes, thanks to information allegedly supplied by John Walker and three other Navy men arrested for espionage.

Adm. James D. Watkins, chief of naval operations, said Tuesday the biggest loss suffered by the Navy was in communications. He said the Navy "assumes" that the Soviets broke the codes designed to scramble messages transmitted throughout the fleet by both teletype and telephone.

Watkins said the Navy is changing its secret communications gear on an "accelerated basis," indicating that at least some of it is similar to that which John Walker repaired and operated while in the Navy. Navy officials said his most sensitive jobs, which gave him access to coding equipment, were at the Navy crypto repair school in Vallejo, Calif., in 1963 and as a radioman cleared for top-secret communications on two nuclear-powered missile-carrying submarines. He was on the missile submarine USS Andrew Jackson from 1962 to 1965 and on the USS Simon Bolivar from 1965 to 1967.

Watkins said the Navy's most vulnerable period was from 1962 to 1969, when Walker was in a position to pass tightly guarded secrets about military communications gear and submarine equipment to the Soviets. Watkins said he believes that the Navy "has bounded the problem" and will replace coding equipment as part of the steps taken to minimize future damage from the secrets believed passed to the Soviets.

Although Watkins did not discuss what could have been compromised by the Walker spy ring, other sources said the coding machines that could have been compromised include the KW 7 and KW 26, used to encode teletype messages, and the KG 13 and KY 9, specialized encryption equipment.

The National Security Agency supplies other coding gear to the military services. Intelligence sources said that, although the equipment Walker had detailed knowledge of is decades old, its components and operating characteristics could help the Soviets penetrate current communications security.

Two former top U.S. intelligence officials disagreed yesterday in estimating the potential loss from compromised communications.

One said the presumed communications compromise could have extended throughout the government, including top-secret intelligence channels. He explained that military services and government agencies use similar equipment to code and decode their messages.

The other former intelligence executive said the coding gear is constantly modified to prevent compromise. He said that reconstructing the machinery would not enable the Soviets to break the codes. They would need a constant supply of key cards, he added, and those are changed continuously to foil attempts at code-breaking.

However, the Walker spy ring could have supplied such cards to the Soviets in the 1960s, Navy officials said. That is one reason they assume some of their codes were broken.