Washington ? U.S. soldiers in Iraq are killing themselves at a high rate despite the work of special teams sent to help troops deal with combat stress, the Pentagon’s top doctor said Wednesday.

Meanwhile, about 2,500 soldiers who have returned from the war on terrorism are having to wait for medical care at bases in the United States, said Dr. William Winkenwerder, assistant secretary of defense for health affairs. The problem of troops on “medical extension” is likely to get worse as the Pentagon rotates hundreds of thousands of troops into and out of Iraq this spring, he said.

Both situations illustrate the stresses placed on the troops and the military’s health system by the war in Iraq.

Suicide has become such a pressing issue that the Army sent an assessment team to Iraq late last year to see if anything more could be done to prevent troops from killing themselves. The Army also began offering more counseling to returning troops after several soldiers at Fort Bragg, N.C., killed their wives and themselves after returning home from Afghanistan.

Winkenwerder said the military has documented 21 suicides during 2003 among troops involved in the Iraq war. Eighteen of those were Army soldiers, he said.

That’s a suicide rate for soldiers in Iraq of about 13.5 per 100,000, Winkenwerder said. In 2002, the Army reported an overall suicide rate of 10.9 per 100,000.

The overall suicide rate nationwide during 2001 was 10.7 per 100,000, according to the federal Centers for Disease Control and Prevention.

By contrast, two U.S. military personnel killed themselves during the 1991 Persian Gulf War, although that conflict only lasted about a month. The Army recorded 102 suicides during 1991 for a rate of 14.4 per 100,000. The Army’s highest suicide rate in recent years came in 1993, when the rate was 15.7 per 100,000.

The Marine Corps has the military’s highest suicide rate. Last year the Marines’ rate was 12.6 per 100,000. During 1993, the Marines’ rate was 20.9 per 100,000.

In 1993, there was U.S. military action in Somalia and Haiti.

The military has nine combat stress teams in Iraq to help treat troops’ mental health problems, and each division has a psychiatrist, psychologist and social worker, Winkenwerder said. Of more than 10,000 troops medically evacuated from Iraq, between 300 and 400 were sent outside the country for treatment of mental health problems, he said.