MISAWA AIR BASE, Japan — Military support is continuing to flow to South Asia more than a week after the region was devastated by the worst tsunami on record.

Some 400 Marines with six CH-46 medium-lift helicopters and other engineering and medical equipment left Okinawa aboard the USS Fort McHenry on Tuesday en route to Indonesia as part of U.S. Support Group-Indonesia, according to Pacific Command officials.

And from Misawa, the 35th Fighter Wing was preparing to send about 23 people from communications, medical, public affairs and possibly finance units on a C-5 military aircraft from Travis Air Force Base, Calif., according to base officials.

The flight was to leave either Wednesday night or Thursday, said 1st Lt. James Lage, base spokesman, and was to stop in Thailand, Sri Lanka and Indonesia.

The initial deployment is slated to last 45 days, but that could change, said Capt. John Haynes, Misawa’s public affairs chief. Haynes is headed to Utapao, Thailand, the hub for U.S. forces operating in the region.

“I think we’re all hoping we can wrap up what needs to be done as quickly as possible, but we’re prepared to provide support for the long haul,” he said.

As of Wednesday, 13,003 Pacific Command personnel were involved in relief efforts throughout the region, according to PACOM.

The Navy this week sent another ship to the region: The USS Niagara Falls is under way from Guam with additional helicopters, PACOM Commander Adm. Thomas B. Fargo said in a Pentagon news briefing Tuesday.

PACOM officials noted that assessment teams still are in the area determining needs and that more personnel and resources could be sent.

Fargo, in his briefing, said assessments to date have focused on infrastructure, such as useable ports, airfields, bridges and roads.

“We know along the south and east coast of Sri Lanka … some 29 bridges are gone. And we know from looking at the west coast of Sumatra that the devastation is significant and the tsunami went well inland in terms of its level of destruction,” he said.

Almost 12,000 of the total number of military personnel deployed to South Asia are at sea, Fargo said. About 1,000 are in Thailand and between 100 and 200 are spread through Indonesia, Sri Lanka and Malaysia.

“As we bring ships like Fort McHenry and Niagara Falls into play, and other units, these numbers will increase by 10, 15 percent,” he said.

The bulk of Misawa’s initial contribution was a communications package of 11 pallets and 20 personnel from 35th Communications Squadron, en route to Bandaranaike, Sri Lanka, according to base officials.

“That’s enough people and equipment to set up a self-sustaining, deployed communications unit” with radio, telephones, computer, secure and non-secure computer communications, secure telephone lines and a public address system, Lage said.

Staff Sgt. Ronell Taylor, 35th Communications Squadron unit deployment manager, said squadron personnel would operate an airfield command and control center for air relief operations, probably out of a tent. Deploying airmen had packed a five-day supply of Meals, Ready to Eat and potable water to last two to three days.

“It wasn’t a requirement but we figured just in case,” Taylor said.

Misawa also was to send a flight surgeon and two medical technicians from the 35th Medical Group. Flight surgeon Capt. Jon Gilbert said he had orders to Utapao.

“The details are sketchy,” he said. “I don’t know if I’ll be sent forward to aid refugees or survivors or stay behind to support the troops there.”

It’s the kind of mission that’s so easy to put “heart, body and soul” into, he said. “Obviously people are suffering. That’s what the medical profession is about, helping people who are suffering.”

For survivors, “clean drinking water seems to be the most pressing need, as well as finding clothing and shelter,” Gilbert said.

The World Health Organization estimates more than 500,000 people are injured and need medical care across six Asian nations.

The death toll from the natural disaster stands at about 150,000 but continues to climb; millions have been left homeless.

David Allen contributed to this story.