BUENOS AIRES, JUNE 3 -- Argentina's military is back.

Three and a half years after surrendering power in disgrace and watching former commanders stand trial, the military has reemerged as a political player and blocked further prosecution of many officers accused of crimes during an antiguerrilla campaign in the 1970s.

While disclaiming any interest in seizing control of the nation again, senior active-duty officers in recent weeks have become more assertive in public, defending the repression of the 1970s, demanding an end to vilification for it and calling for increased military spending.

"From 1983 until recently, the armed forces suffered largely in silence," said a retired Army general close to the current leadership. "They felt aggrieved, persecuted by the government and the media. Now they are speaking out. More importantly, they are being heard."

Although still unpopular with a large majority of Argentines for having bankrupted the economy, lost a war to Britain over the Falkland Islands and killed more than 9,000 persons in combatting subversion, the military's comeback is linked to its demonstrated ability to disrupt the slow consolidation of Argentina's democracy.

Since April when dozens of officers revolted at several Army bases, the government has rushed to end many of the human rights trials that generated the protests. It also has promised a new military policy more responsive to problems of budget cuts, aging equipment, low salaries and a yet-to-be-defined role for the armed forces under democracy.

The skillful defusing of the Easter Week rebellions by President Raul Alfonsin had looked at first like a political victory. The administration's success in rallying hundreds of thousands of civilians in open support for democracy affirmed Alfonsin's popularity and presented a bulwark against any potential military grab for power.

But in retrospect, the uprisings marked a watershed for the armed forces as well.

"The first 40 months of democracy occurred under the shadow of military power," observed James Nielson, a former editor of the Buenos Aires Herald. "All were conscious of its existence; nevertheless, it was possible to minimize its importance, to try to believe that the military would conform to a secondary role. But since Easter Week, no one can assume such a luxury.

"The pendular swings, so typical of Argentine politics over the past half-century in which power has oscillated between strong military and weak civilian regimes, have not been overcome. On the contrary, the pendulum is newly in motion, and stopping it will not be easy."

Other young South American democracies, also trying to break the regional custom of military tutelage of civilian society, are closely watching what happens in Argentina. In Ecuador, Peru and Brazil, the armed forces continue to protect their interests forcefully. The immediate challenge for governments there as here is not so much to avoid a coup as it is to enlarge the space in which democracy can grow.

Taking power in 1983 after nearly eight years of military rule, the Alfonsin administration considered it morally necessary and politically advantageous to bring military officers to trial. But the process has lasted longer than some senior presidential aides had anticipated, implicated more officers than expected -- between 250 and 400 -- and brought unrest in the ranks to a boil.

The lower house of Congress is due Thursday to approve a bill, already passed by the Senate, that would shield all lower-ranking officers from prosecution for murders, torture and illegal arrests committed during the so-called "dirty war" against leftist subversion. Army colonels and brigadier generals, and those of equivalent rank in the Navy and Air Force, also will be excused from trial if federal courts determine that they, like their subordinates, were following orders.

Among the scores of mutineers, mostly middle-ranking officers, involved in the April uprisings, only several face trial. Lt. Col. Aldo Rico, who led the main uprising at the Campo de Mayo base on the outskirts of Buenos Aires, has continued, in detention, to receive visits from fellow officers, politicians and others.

Gen. Jose Caridi, the new Army chief of staff, champions the military's political revival. Appointed immediately after the rebellions to restore discipline in the ranks and rebuild an Army command decimated by the forced retirement of 15 generals, the artillery officer has assumed a more aggressive stance than his recent predecessors.

Caridi pressed Alfonsin and the governing Radical Civic Union to broaden the proposed law, which in its original form exonerated officers from the rank of lieutenant colonel down. In hard-edged speeches during the past week, the Army leader has staunchly defended the antiguerrilla war. Although appealing for national reconciliation, the most that Caridi has offered publicly in return for an end to the trials is the Army's commitment to help reorganize itself into more efficient fighting units.

The absence of any self-criticism on the military's part regarding the brutal tactics used to wipe out leftist subversion has upset legislators ready to strike a compromise.

Marcelo Stubrin, a senior Radical party deputy, called the military's unyielding attitude a "significant obstacle" to the development of Argentine democracy. Added Adolfo Gass, a Radical party senator: "We speak of reconciliation, but for that, two parties are needed. Where is the gesture by the other side?"

Military sources say tough talk from Caridi and his deputy, Gen. Fausto Gonzalez, is necessary if the generals are to establish credibility with their troops.

The new commanders are mindful that the April uprisings were sparked partly by a perception that their predecessors had been out of touch with lower-ranking officers and too accommodating to civilian authorities.

Moreover, the military leaders are eager to hold in check antidemocratic groups within the armed forces -- what Caridi has called the unacceptable growth of a "parallel army." Alfonsin thus finds it in the national interest to try to bolster Army commanders who support democracy.

The Easter uprisings have given the Argentine leader a new chance to redraft a military policy that until now has done little to improve the armed forces and much to upset them in the form of military spending cuts and the trials.

Human rights activists see the new legislation not as an opening to better civilian-military relations but as a misguided retreat by Alfonsin that is bound to weaken civilian authority.

Further, the military's own mind set, unchanged under democracy so far, is apt to keep it on the margin of Argentine society. The armed forces remain a deeply conservative institution, intensely nationalistic, fanatically anti-Marxist and innately doubtful of the competence of civilian governments to handle military affairs.

Some officers have made it clear they will only be satisfied when all the trials are ended and an amnesty is declared to restore the military's damaged sense of honor. Although Alfonsin continues to rule out an amnesty on principle, some here would not be surprised to see it happen sometime after the Sept. 6 gubernatorial and congressional elections.