The first wave of U.S. troops to join the battle against disease and starvation in cyclone-devastated Bangladesh Monday scouted out possible sites along the sea coast for water purification units.

Also, a giant U.S. Air Force C-5 Galaxy transport plane landed in Dhaka Monday with five badly needed helicopters that will be used to ferry supplies to storm survivors.Millions of people are threatened by sickness, hunger and exposure following the April 30 cyclone that killed more than 139,000 people, many of whom lived on low-lying islands and in coastal villages along the Bay of Bengal.

The first advance teams for the American military task force arrived in Dhaka on Sunday, and 170 soldiers had arrived by Monday night. They were about equally drawn from the Army, Air Force, Navy and Marines.

Altogether, more than 12,000 U.S. troops - including Persian Gulf war veterans - are to contribute to the international effort to save storm survivors.

Most were expected to arrive by sea Wednesday or soon after aboard the amphibious assault ship USS Tarawa and the seven other vessels accompanying it. The Marines on the Tarawa had been headed for to Camp Pendleton in California when they were diverted to help with the relief effort.

Some of the most useful equipment coming with this group is likely to be hovercraft that can scoot over the swamped shores of the Bay of Bengal.

The United States has provided $7.2 million in emergency cyclone aid, but the U.S. Embassy channels funds and distribution through non-profit groups such as CARE, one of the most active organizations in the area.

As the misery continued in the southeast, more bad weather struck other parts of Bangladesh. High wind warnings were issued, but none of the new storms and floods approached the intensity of the killer cyclone.

As the U.S. military began its relief efforts, the weather bureau said squalls might hit Dhaka and five other cities - covering virtually every part of the country except the area struck by the cyclone.