A move last week by the Argentine government to accelerate trials against hundreds of military officers has given a push to stalled efforts to account for crimes committed in the 1970s war on subversion.

But parallel attempts to define a new role for the armed forces and to restructure and modernize them continue to lag. Moreover, the acquittal by the military's highest court of a naval officer in the 1977 disappearance of a 17-year-old Swedish-Argentine girl has drawn denunciations from human rights activists. They accuse the civilian government elected three years ago of relaxing its commitment.

President Raul Alfonsin's dealings with the military represent a bold departure on a continent where a number of other recently elected governments are similarly groping for a new order of civilian-military relations. In the past seven years, civilian administrations have replaced military regimes in Ecuador, Peru, Bolivia, Uruguay, Brazil and Argentina.

The Argentine military has been in and out of power for the last 56 years and was long regarded as one of the most aggressive and political in Latin America. Remaking it into a professional force subordinated to civilian authority has been a top priority for Alfonsin.

The Argentine leader has slashed military spending by half, removed 50 of 53 generals who were on duty at the start of his term, made commanders submit to a civilian-run Defense Ministry and sought to strengthen the position of a solitary chief of staff over divisive Army, Navy and Air Force branches.

But despite these budgetary and personnel moves, there has been no major restructuring of military units. The structure of forces remains essentially as it was during the 1982 war against Britain over the Falkland Islands. Argentina's defeat in that battle triggered the end of military rule here.

The draft of a new law on defense, which would make the military responsible for defending only against external attack, not internal subversion, is stalled in the Senate by Peronist and provincial party opposition. The law would merge under the Defense Ministry the intelligence agencies now run by each service and would establish an all-civilian national security council, giving the military a decision-making role only in time of war.

"The government has succeeded in taking away the political role of the armed forces in Argentina, but it still hasn't answered the question of 'What are you going to do with them now?' " said Virginia Gamba, a professor at the country's National War College.

Resentment among military personnel against Alfonsin is deepest over the prosecution of officers for murders, tortures and kidnapings during the military's campaign against leftist dissidents starting in the mid-1970s. Marking the first instance here of a civilian court judging the military, a federal appeals panel in December convicted five former junta members of crimes in connection with what is known as "the dirty war." Four other ex-commanders were acquitted.

With about 1,700 other cases pending but seeming to go nowhere, the government last week ordered the remaining trials speeded up. In a letter to Hector Canale, the military court's prosecutor, Defense Minister German Lopez said a "multiplication of trials and charges" had slowed the proceedings and were in danger of becoming "a disorder." He also said the proliferation of cases had projected "an image of collective judgment" against the military, which had damaged morale and was contrary to the aim of the investigations.

The minister told Canale to group similar cases for trial. He said charges should not be brought against officers who were exercising "due obedience" -- that is, following orders -- except in those cases where subordinate officers "knew the illegality of the orders or carried out atrocities or aberrations."

Human rights activists have criticized the instructions because the determination of what constitutes "due obedience" is to be left to each judge. This, say human rights spokesmen, could lead to impunity for some lower-ranking officers.

Seeming to confirm such fears, the Armed Forces Supreme Council decided last week to acquit Navy Lt. Cmdr. Alfredo Astiz of involvement in the case of Dagmar Hagelin, a Swedish-Argentine girl who disappeared here in January 1977 on her way to a friend's house. She reportedly was kidnaped by Navy functionaries and is believed to have died in detention. The nine-judge military tribunal, which is responsible for investigating such cases, concluded there was a lack of evidence.

The naval officer, who fought in the Falklands war and surrendered to the British, gained international attention as the only Argentine military man taken to London. He was sought by Sweden for questioning in the Hagelin case and by France in connection with the abduction and suspected murder in Argentina in 1977 of two French nuns. But Britain, citing the Geneva convention on prisoners of war, returned Astiz to Argentina.

Government officials have denied that their aim is to amnesty any of the accused and say the new instructions should be read simply as an impetus to get on with the trials, which involve about 300 accused officers, some of whom have been accused in more than one case. If delays persist, the federal appeals court has the right to take over a case, as it did that of the junta leaders.

Army Chief of Staff Hector Rios Erenu said the defense minister's instructions, drafted in consultation with the military, would lift "the climate of unease" in the armed forces.

The Navy chief, Vice Adm. Ramon Arosa recently spoke out bitterly about Argentines who once applauded the armed forces and "now turn their backs on us." He said his men "know what it is to suffer the pain of incomprehension and ingratitude."

Government officials contend the trials were necessary as a response to public pressure to account for the past. The judicial process, they say, has benefited the cause of democracy by exposing the military's abuse of power.

When they took office, Alfonsin and his aides knew little about military strategies, organization and technology. Civilians in this country have traditionally been kept in the dark about military affairs, lacking the think tanks and information sources that exist in this field in the United States and Europe.

"Most military changes up to now have not been deliberate but the result of budgetary cuts," said Marcelo Cavarozzi, a prominent political scientist.

Argentina's current austerity drive has itself put a break on military change. Although investments in new equipment and the shifting of troops away from Buenos Aires -- where units are disproportionately concentrated -- could mean greater effectiveness, the cost is a deterrent.

Defense spending has been cut to about what it was, in percentage of national output, before the military took power in 1976. Its projected level this year is 2.3 percent of gross national product. Cuts have meant a drop in conscripts from 108,000 in 1981 to 37,000 this year, fewer training exercises and shorter operating hours at some military bases. Salaries, too, have been held down.

The Argentine military is a corporate power, running factories, schools and airports and employing thousands of civilians. Part of the government's long-range plan involves turning these functions over to civilian managers and getting the armed forces to focus on more conventional military activities.

Also under study is how to improve coordination between the services, each of which has had its own system of planning, training, intelligence and communication. To this end, Alfonsin has enhanced the role of the unified chief of staff. This post, which used to be given to Army generals, was filled last year by an Air Force brigadier. The Air Force emerged less tarnished than the Army and Navy from both the Falklands war and the earlier repression.