ROCKLAND – In another time, the announcement heard over radio scanners Friday morning might have elicited a “Hmmm” of interest, at most.

But after the attacks of Sept. 11, the warning to mariners that the U.S. Coast Guard would be conducting a training exercise with “live” ammunition portends much more.

Kyle Santheson, the commanding officer of the Coast Guard’s Rockland station, said Friday the training is actually a routine event. The Coast Guard conducts such training exercises annually, he said, to keep crew current with their qualifications to use weapons, and to ensure the equipment is working as it should.

In Maine, many people associate the Coast Guard with the rescue of boats in distress and with tending buoys and keeping shipping lanes on the Penobscot River free of ice. But the Coast Guard is, in fact, a branch of the military, Santheson said, and is charged with law enforcement and protection.

Santheson would not reveal what types of weapons were being fired Friday, but said the vessel was about six miles southwest of Matinicus Island at the mouth of Penobscot Bay. The weapons are not fired until the area is scanned, both visually and with radar, to be sure no vessels or aircraft are in the area, he said.

“We’re more than five miles from any land,” Santheson said.

The weapons are fired at targets, he said.

“It’s a readiness thing we go through for homeland defense,” he added.

Santheson agreed that notice of the exercises would have “gone in one ear and out the other” to anyone listening on marine radio or a scanner a year ago. But since the country is on heightened alert after the terrorist attacks, news of such activities are more likely to be noticed.