A military spokesman says the Marine reservists are men and women who returned to civilian life after previous active duty service. They will fill critical shortages among military police units, intelligence and communications specialists.

President Bush issued an order authorizing the involuntary callup.

The Marines Corps has 35,000 reserve troops with time remaining on eight-year commitments made when they enlisted. Mr. Bush's order limits the number of those who can be recalled to 2,500 at a time. The reservists are expected to return to active duty for 18 months.

Meanwhile, in Iraq, U.S. military officials report a declining trend in violence this month in Baghdad. They say combined American and Iraqi forces captured more than 100 known or suspected al-Qaida terrorists in the past week.