MANILA -- The murder of U.S. military personnel by communist insurgents, overriding President Corazon Aquino's attempts to show stronger leadership, has revived talk of a new and more highly placed coup attempt against her.

The real threat comes not from the celebrated rebel, Col. Gregorio (Gringo) Honasan, but from senior officers frustrated that Aquino lacks the will to destroy the communist insurrection. Since the United States repeatedly has warned that a coup would instantly cut off indispensable American aid, frustration has to be very high for officers even to consider moving against her.

The U.S. position is that whatever her shortcomings, there is no viable alternative and that Aquino's overthrow would spell disaster. But Manila is so grim that Aquino's enemies may be willing to pay this high price. Tourist and investment dollars, in short supply anyway, are dried up by the killing of American servicemen. To freshen the atmosphere will take more than the president's recent hard-nosed speech to businessmen.

That speech, declaring war on coup-minded officers and the communist insurrection, reduced the unease that is gripping American diplomats, who desperately want her to succeed. But whatever lift her rhetoric provided was diminished by the communist death squads.

Gen. Rafael Ileto, secretary of national defense, told us the guerrillas ''must be desperate. . . . They have to do something like this because they are on the losing end.'' But his predecessor and current opposition leader, Sen. Juan Ponce Enrile, in a separate interview said this ''was not an act of desperation'' but ''of boldness on their part . . . confidence that they can now really even tackle the superpower ally of the Philippines.''

Enrile's view is shared within the uniformed military, from junior officers to senior generals who argue the war is indifferently managed. It is here, not from exiled former president Ferdinand Marcos or the fugitive Honasan, that serious coup danger lurks. One anti-Aquino politician listed for us by name a dozen senior officers as potential coup perpetrators before year's end.

Not among those names was Brig. Gen. Rudolfo Biazon, famed for fighting the communists on Mindanao before being appointed Marine Corps commandant. No senior officer is more loyal to his president. Consequently, what he told us is chilling.

While careful not to criticize Aquino, Biazon left no doubt that he believes the communists have gained ground with 24,000 guerrillas in the field and that much more government effort is needed to win ''mass support.'' ''The government is not there yet,'' he said. He fears the Aquino regime may be so ''pulled and pushed'' by the revolutionary left and the disloyal right that ''the vital center turns into a power vacuum.''

The problem is partly priorities. Aquino loyalists in the defense establishment such as Ileto and Biazon put first suppression of the communist insurrection, but the civilian government is ambivalent. Dr. Emmanuel Soriano, recently named Cabinet-level national security counsel, told us the ''immediate problem'' is posed by military right-wing rebels.

Accordingly, increased terror is attributed by one key policy maker not to the communists but to ''diehard Marcos loyalists.'' He claims intelligence shows a clumsy dynamite bomb found just in time at the Manila Convention Center, site of the forthcoming ASEAN summit, was made from explosives stolen by Marcos agents from a construction site.

That at least is possible. But even friendly diplomats dismiss the notion by government officials that recent bombing of bridges and power grids was the work of Marcos diehards, not the communists. To the military, that connotes an insufficient appreciation of the guerrillas, feeding the frustration that led to Gringo Honasan's bloody coup attempt in August.

While available for press interviews, Honasan is beyond the government's reach -- partly because of his popularity. ''It's easy for him to hide amidst all of his friends and people who are protecting him,'' Secretary Ileto told us. One retired officer, always anti-Marcos and an early Aquino booster, explained why the outlaw colonel is at large: ''How can you arrest a hero?''

Still more popular than Honasan, however, is Cory Aquino -- as her most strident critics concede. Even Enrile does not attack her frontally but says, to forestall further coup attempts, ''she must govern; she must not delegate the power of governing to her subalterns.'' This view is so pervasive in the military that if officers decide on a coup, says Enrile, ''they really do not care whether America will cut off aid or give aid to the Philippines at that point.'' For the sake of both countries, that point must be averted.