ANDERSEN AIR FORCE BASE, Guam  To take part in its annual exercises with the United States Air Force here last month, Japan practiced dropping 500-pound live bombs on Farallon de Medinilla, a tiny island in the western Pacific’s turquoise waters more than 150 miles north of here.

The pilots described dropping a live bomb for the first time  shouting “shack!” to signal a direct hit  and seeing the fireball from aloft.

“The level of tension was just different,” said Capt. Tetsuya Nagata, 35, stepping down from his cockpit onto the sunbaked tarmac.

The exercise would have been unremarkable for almost any other military, but it was highly significant for Japan, a country still restrained by a Constitution that renounces war and allows forces only for its defense. Dropping live bombs on land had long been considered too offensive, so much so that Japan does not have a single live-bombing range.