Perry Earns High Marks in New Job : He’s erasing vestiges of Aspin’s reign and is succeeding in public policy role.

In just four weeks, the nation’s new defense secretary, 66-year-old William J. Perry, has begun making significant changes in both the style and the structure of the Pentagon’s operations, earning early high marks within the Defense Department and outside.

Perhaps the most visible change has been Perry’s rapid dismantling of the awkward--and highly controversial--”little State Department” created in the Pentagon by his predecessor, Les Aspin, to handle peacekeeping, human rights and other post-Cold War challenges.

Convinced that the Aspin-backed think tank had become a political liability, Perry downgraded the idea shop to a far less-influential role. And he has scrapped two assistant secretary jobs in that area, shifting them to more traditional Pentagon offices.

Insiders say he is restoring a sense of direction to the secretary’s office, in part by making decisions more promptly and clearly than was Aspin’s wont. And his workdays and trips abroad are a model of punctuality and order.

But the real surprise has been in Perry’s seeming success so far in the public policy part of the job. Despite critics’ suggestions that he was too much a technocrat, for such a role, he has proved a serious player in top policy-making circles--and an articulate policy spokesman.

When the White House was pondering whether to launch air strikes in Bosnia last month, for example, it was Perry who insisted on limiting any NATO threat to what was achievable militarily, dampening enthusiasm by White House staffers for taking on a more ambitious role.

And just before the Feb. 20 NATO deadline for withdrawal of Serb artillery from the Sarajevo area, he called allied defense ministers to a meeting in Italy to make sure their governments were still prepared to enforce the threat if necessary.

Barry Pozen, a Massachusetts Institute of Technology geopolitical analyst, says the fact that Perry was able to make the Pentagon’s voice heard in the Administration’s deliberations on NATO’s action in Bosnia represents a marked contrast from previous days.

Pozen says one of the problems with the Administration’s policy-making during Aspin’s tenure was that the former Wisconsin congressman was not able to bring the Defense Department’s reservations to the table forcefully enough.

On Capitol Hill, Perry is demonstrating an ability to field complex foreign policy questions at hearings and to provide lawmakers with concise answers that appear to reassure them, even when they disagree with a policy.

“He’s a breath of fresh air,” one key Congress-watcher said after a meeting of the House Armed Services Committee last month. “He knows what he’s talking about and he’s not afraid to answer straight-out.”

Still, Perry’s performance as an Administration spokesman has had its flaws. Visibly nervous during sessions with reporters, Perry spent the better part of a nationwide TV interview show looking “like a deer in the headlights,” one outside critic complained.

Pervading Perry’s first weeks has been the inevitable contrast with Aspin, who was viewed as disorganized and inarticulate--factors that White House officials say led to his forced resignation last December in the midst of mounting criticism.

Although the new secretary has conspicuously avoided public comparisons with Aspin, he clearly has taken pains to avoid repeating Aspin’s mistakes. He is careful about framing answers to questions, taking time, if need be, to think out what he is about to say.

Despite Perry’s initial success in the job, some onlookers question whether he can go a needed step further and become a dominant enough force in top policy-making circles to put the Administration’s overall foreign policy in order.