‘Friendly Fire’ Killed 2 GIs in Panama : Invasion: The Pentagon sharply increases its estimate of U.S. casualties inflicted by own forces.

WASHINGTON —  Two U.S. servicemen were killed and 19 were wounded by gunfire from their comrades during the December invasion of Panama, a significant increase from previous official estimates of casualties from “friendly fire,” the Pentagon acknowledged Monday.

A third death and 21 other injuries remain under investigation to determine whether the casualties were caused by hostile or friendly fire, a Defense Department spokesman said.

The Pentagon previously had announced that five GIs were wounded and none killed by other American troops. It released the updated figures in response to a Newsweek article published Monday, which said that nine deaths and as many as 60% of the injuries were inflicted by American troops.

Twenty-three GIs were killed and 324 were wounded in the invasion, which involved 24,000 U.S. troops. The aim of the brief war, dubbed “Operation Just Cause” by military planners, was to restore democracy and bring former dictator Manuel A. Noriega to trial on drug charges in the United States.

While the friendly fire casualties are not markedly high by historical standards, they serve as further confirmation that the operation was not as smooth nor as highly disciplined as first portrayed by senior military officials.

White House spokesman Marlin Fitzwater declined Monday to respond to the Newsweek report, but he said: “We continue to believe that the Panama invasion was very effectively, efficiently carried out,” given the “complexity of the operation.”

The two U.S. soldiers accidentally killed by their fellow troops were part of an elite contingent of 850 Army Rangers who launched a night-time parachute assault on a Panamanian military camp at Rio Hato, the Pentagon said.

A Pentagon spokesman provided no further details about circumstances of their deaths. The raid claimed the highest concentration of Army casualties of any operation during the invasion, leaving one in 18 Americans dead or wounded.

The Pentagon has since acknowledged that the raid began in some confusion when an F-117 Stealth fighter assigned to drop a 2,000-pound bomb adjacent to a Panamanian Defense Forces barracks missed its target badly. Officials said that the error may have diminished the intended effect of stunning the enemy.

The Rio Hato assault was one of the last Panama invasion operations to be planned. Military sources have said that the hurried preparations could account for the high number of casualties.

Military officials released no further information about the circumstances that led to the killing of the one U.S. soldier whose death is still being investigated or about the 19 American servicemen acknowledged to have been wounded by friendly fire during the invasion.

They said, however, that 21 additional U.S. soldiers may have been injured by friendly fire during intense night fighting near the Comandancia, a five-story military headquarters building in a crowded Panama City neighborhood.

That assault brought U.S. troops under fire from all directions as snipers opened fire from surrounding high-rise apartment buildings. For that reason, the Pentagon said that it had been unable to “distinguish which of the 21 were hit by friendly or enemy fire.”

Times staff writer Douglas Jehl contributed to this report.