a blue-checked shirt and wearing sunglasses, Kerry is surrounded by aides and other officials on the boat but he is mostly quiet and introspective.

"It hasn't changed all that much," Kerry remarks at one point during the tour. The familiar smell of burning firewood in the air coming from villages takes him back to his time on the river.

At the small riverside community of Kien Vang, translated roughly as "the golden ant", Kerry stops to take a walk, visiting a small convenience store where he buys candy for the local children. There he pets a dog and is reminded of a mutt he adopted while serving in Vietnam he named "VC" - short for Viet Cong.

Here he also inquires from Dang Kieu Nhan, deputy director of the Mekong DeltaDevelopment Research Institute, about water levels and how possible changes in water flows on the river will affect villagers.

His concern is not only the effects of climate change on the Mekong but also plans by China to build four more dams along the Mekong to generate power for its rising economy, projects that will have a disastrous downstream impact on Cambodia and Vietnam, according to environmental specialists.

In addition Laos is also proposing to build hydropower plants on the Mekong, while Cambodia has plants for two dams on the river.

Across the canal, Kerry addresses these developments in a speech to the students, while also pledging $17 million to a program to address the impact from potential climate changes.

"No one country has the right to deprive another country of the