Defense Secretary Harold Brown said yesterday that it "will take about a year" to regain the ability "verify adequately" whether the Soviets are living up to the missile provisions in the SALT II agreement.

The loss of monitoring stations in Iran, Brown conceded in his statement issued by the Pentagon last night, was a setback but only a temporary one.

He agreed with Central Intelligence Agency Director Stansfield Turner that "regaining all of this monitoring capability" lost in Iran "will take until 1983 or 1984, depending on how much we are able to accelerate programs already under way."

However, Brown said as the verification argument heated up, the United States does not need all that capability to determine whether the Soviets were cheating.

"Regaining enough" of the lost monitoring ability "to verify adequately Soviet compliance with the provisions of SALT II, I estimate, will take about a year," Brown said, "depending on how fast we can carry out monitoring programs under development."

The Pentagon and CIA are rushing ahead with a number of new generation of spy satelites that would watch Soviet missile and submarine deployment as well as track missiles being tested.

The Carter administration now plans to spend about $100 million extra on these satelites to get them into space about 10 months sooner than originally planned. The target operational date is 1983.

Another idea is to rig U2 spy planes with antennae especially designed to track Soviet missiles during test firings.

The National Security Agency also has monitoring stations in Turkey watching Soviet missile activity. These sites are expected to be upgraded.

The administration's recent moves to compensate for the loss of Iranian eavesdropping facilities, and Brown's unusual public statement yesterday, are part of a concerted effort to persuade skeptics in theSenate that the administration is highly sensitive to the problems of verifying Soviet compliance with a SALT pact.

A senior official acknowledged yesterday that repeated assertions that SALT II cannot be verified can erode the administration's credibility, whether the statement are justified or not.*tAdministration officials were upset by a report in yesterday's New York Times quoting Turner as telling senators last week it would take five years to fully make up for the loss of intelligence-gathering assests in Iran. The Tines story and wire service accounts based on it prompted Brown's statement last night.*tThomas B. Ross, assistant secretary of defense for public affairs, said last night that the Pentagon issued Brown's statement "to set the record straight" after some reports on Thuner's views failed "to rocus on the shadings" of U.S. verification abilities.

Said Brown:

"The principal information at issue is the nature and characteristics of new or modified Soviet intercontal ballistic missiles. Each such Soviet program will require about 20 flight tests over a period of years.

Though existing monitoring systems or replacements for the Iranian sites could well miss some flights, and might miss some data from some flights that they see, our assessment of compliance" with SALT II "would be made from the information we would collect over the whole test program for each missile from a variety of monitoring systems.

"We expect to conclude a treaty that resolves satisfactorily the remaining provisions on verification and on new ICBMs. In that event, it is my judgement that our monitoring will be such as to provide adequate verification as to Soviet compliance with the curbs on new or modified ICBMs.

"Brown and Turner have been at odds in the past over how the U.S. intelligence effort should be organized. Ross answered "no" last night when asked if the two officials are now in disagreement over U.S. ability to monitor the SALT II agreement.

Administration sources said plans had been considered for accelerating the new spy satelitte program even faster than has now been agreed, but the idea was rejected because it would have required eliminating some capabilities from the powerful new satellites.

They also said the United states is hoping to be able to exploit new listening posts on the ground around the periphery of the Soviet Union, but declined to say where such posts might be located.