The Defense Department has activated more than 20,000 more Army troops to be sent to the Persian Gulf as the U.S. military buildup continues for a possible war with Iraq, Pentagon officials said Tuesday.

Deployment orders signed by Defense Secretary Donald H. Rumsfeld over the weekend will send the Army's 3rd Armored Cavalry Regiment and several smaller units to the area around Iraq, where they will join about 150,000 other U.S. forces already in the region.

The other units include an artillery brigade, a combat support hospital, a chemical weapons defense company, a military police unit, "civil affairs" specialists in humanitarian missions and rear area support units, officials said.

The latest deployment is part of a steady stream of American military personnel being sent to the region in case President Bush decides to go to war to topple Iraqi leader Saddam Hussein. Bush has said time is running out for Saddam to give up his banned weapons of mass destruction before U.S. takes military action.

The 3rd Armored Cavalry Regiment has more than 300 tanks and armored vehicles, as well as helicopters like the AH-64 Apache. The unit is trained for fast, long-range, armored strikes such as the one analysts say is likely to form the core of any U.S. ground invasion of Iraq.

The regiment, based in Fort Carson, Colo., has about 6,000 soldiers and support staff.

Meanwhile, an Air Force Reserve unit that specializes in airlifting wounded soldiers to military hospitals, among other missions, announced that more than 300 of its personnel have been activated for possible assignment to the Persian Gulf region.

The members of the 445th Airlift Wing, based at Wright-Patterson Air Force Base near Dayton, Ohio, fly and maintain C-141C Starlifter cargo planes. Each plane can carry more than 47 tons of cargo, including either 103 patients with attendants, 168 paratroopers or 208 troops.

The wing has flown about half of the 600 or so suspected Al Qaeda or Taliban prisoners to the lockup at the U.S. Navy base in Guantanamo Bay, Cuba.