Updated

The military expects to put 30,000 National Guard (search) troops on duty in the Gulf states as demands grow for more security and relief assistance, the commander in charge of military relief and rescue efforts said Thursday.

About 24,000 of those will be on the ground in Louisiana and Mississippi in the next three days, Army Lt. Gen. Russel Honore said in a telephone interview with reporters at the Pentagon (search). He also ordered the amphibious assault ship USS Bataan (search) from the Louisiana coast to waters off Biloxi, Miss., to assist with hurricane relief operations there.

The additional Guard units, plus active duty troops responding to the disaster, brings the total military complement to more than 40,000.

Also, the Army has notified commanders at four or five major bases, including Fort Hood (search), Texas, and Fort Bragg, N.C., to stand by for further word on whether they may be required to send troops to the hurricane-stricken area, according to several defense officials who spoke on condition of anonymity because no final decisions had been made.

"We continue to build our capability," Honore said. "It's a trying situation at best, and the enormity of the task is significant."

A majority of the troops, he said, will be used for security to augment state and local police.

The troops were struggling to get to people in need, and to clear roads to facilitate rescues and levee repairs needed to stem the flood waters.

"It's hard to imagine, but our people had to literally chain saw their route to the base," said Air Force Col. Jim Lyon, commander the 823rd Red Horse Squadron. "They found roads impassible and had to hunt for alternate routes. "

Coast Guard Petty Officer Keric Allen, who spent two nights pulling injured people and families off New Orleans and Gulfport, Miss., rooftops, said helicopter pilots just head for the flashlight beams that victims wave as they wait desperately for help.

"It's hard because I'll land on a rooftop and I can hear a guy yelling from a half a mile away, calling for help. You just hope that you don't run out of gas or have to go home before you get to them," said Allen in a phone call from Gulfport.

Defense Secretary Donald H. Rumsfeld and Lt. Gen. Steven Blum, commander of National Guard forces, met with President Bush Thursday to brief him on the military response.

Earlier Thursday, officials said the aircraft carrier USS Harry S. Truman was heading to the Gulf Coast to serve as a floating command center for Hurricane Katrina relief operations.

The Truman and the dock landing ship USS Whidbey Island will join five other Norfolk-based Navy ships that were already under way or in the Gulf as part of the Defense Department contingent being deployed to the stricken region. The hospital ship USNS Comfort is expected to reach the Gulf Coast by next Thursday, and a fast combat support ship based at Naval Station Earl in New Jersey and a rescue and salvage ship were also en route. The Air Force was sending in a U-2 surveillance and reconnaissance aircraft to get detailed, high resolution photographs of the Gulf Coast area.

Marine Corps spokeswoman Capt. Gabrielle Chapin said the Marine Corps Air Station at New River, N.C., had dispatched eight helicopters and at least 120 Marines to the region.

Also, Lt. Col. Bob Thompson, spokesman for Air Force Reserve Command, said volunteer pilots and crews were flying C-130 transports and HH-60 helicopters from Reserve bases in Florida, Alabama and Texas to ferry medical supplies and bring in para-rescue airmen for search and rescue missions in the stricken region.

The military's plans to assist with recovery efforts don't involve a large-scale shifting of U.S. troops from Afghanistan or Iraq, a spokesman for the U.S. Central Command said Thursday.

But the Pentagon is looking at ways to bring home from the war zones individual service members whose families suffered from the hurricane and need their help, said Lt. Col. Trey Cate, based in Qatar.