NOTHING FOCUSES American attention on a distant land faster than the death of an American there. Terrorists, knowing this, are in a position to send an instant message. But what is the message sent by the simultaneous killing of two American servicemen and aFilipino-born U.S. Air Force retiree outside Clark Air Base in the Philippines? Have Communist insurgents finally decided to take on American targets, figuring that the risk of drawing in the United States pales against the opportunity to exploit popular resentment of the American bases? Or -- this is the sort of speculation the miasma in Manila invites -- has the right staged a provocation to dramatize President Corazon Aquino's weakness for an American audience? This hardly exhausts the possible explanations.

Whatever its origin, the event deepens the crisis of Mrs. Aquino's 20-month rule. She first sought reconciliation on the left, choosing co-option and compromise over repression and unending counterinsurgency. But the New People's Army appears to be getting bolder, and the land reform announced to broaden the government's base has stiffened the right, including the landed rich, a segment of society from which Mrs. Aquino comes. She used the military to put muscle behind her successful "people power" challenge to dictator Ferdinand Marcos. But at least five coup attempts have since been launched, and the leader of the last, Col. Gregorio Honasan, flaunts his fugitive status. Her own vice president, Salvador Laurel, almost openly invites the military to put him in power.

Mrs. Aquino acknowledges that people ask "can she hack it? Is she weak?" She means to be strong, something the Philippine political culture demands even as it also demands that she stay true to her democratic promise. Certainly she is beyond asking or receiving any relief on grounds that circumstances are cruel. Nor is it feasible for her to ask directly for too much American help. The aid, or the paltry part of it that is delivered, is welcome, but the reminder of the immense American presence is not.

Washington nonetheless has a responsibility that extends beyond material support. It must stick with the elected president, against buccaneer colonels and against ambitious civilians like Salvador Laurel, the rebel-in-place who seems to hope his rank ensures him continued American backing if he were put into the presidential palace by a "constitutional coup."