Night had already fallen in Manila on Aug. 15, 1945 (on the other side of the International Dateline; it was Aug. 14 here) when a few of us stepped out of the door of our installation at 678 Rizal Avenue to hear a young GI -- the blue stripe of the infantry on his hat -- screaming: "They ain't going to shoot at me anymore! They ain't going to shoot at me anymore!"

Japan, we thus discovered, had thrown in the towel.

In that vignette, I think, lies an answer to guilt- striken Americans who today wonder if we should have dropped "the Bomb" on Japan. Of course we should have. How many GIs like the boy in Manila would have died if we had gone ahead with the planned invasion of Japan's home islands? President Reagan was 100 percent right when, in aswer to a question at his news conference the other day, he said, "I think to second-guess now those who had to make that awesome decision is ridiculous."

That night, when we knew World War II finally was over, a spontaneous parade of Army vehicles -- horns blasting -- coursed the darkened streets of downtown Manila. We jumped in a Jeep and joined the procession. Through clouds of dust, candles twinkled in the huts that Filipinos had fashioned from rubble and scraps of metal. In the distance there was happy rifle fire. For once, we didn't notice the pervasive sweet stench of what I presumed to be bodies still rotting under the crumbled buildings of a city that had proudly called itself "the Pearl of the Orient."

Next day, at the Central Film and Equipment Exchange where I was stationed, those of us in uniform were jubilant at the prospect of going home. But Filipino civilians who worked for us were subdued. Puzzled, I finally asked one of them how the Filipinos felt about the war's end. The answer: "We hoed the war would go on a little longer, so you could drop more atom bombs on Japan." Japanese occupation of the Philippines had been brutal.

Well, 40 years have passed, and it is a different Japan. Today's Japanese would rather make autos than war, and Americans would rather buy autos than fight the Japanese. You do not foster peace by nurturing grudges. But neither do you foster peace by losing perspective, and in 1945 our only realistic goal was the total defeat of a totally ruthless and fanatical enemy -- with the least possible loss of American lives.

The atom bomb gave that young infantryman in Manila a longer life expectancy.