RAJENDRAPUR, BANGLADESH - Nowhere is the potential threat from climate change more worrisome than in Bangladesh, a country that is strategically sandwiched between rising superpowers China and India and that also acts as a bridge between South Asia and Southeast Asia.

Bangladesh is beset by extreme poverty, overcrowding and flooding that frequently renders large numbers of people homeless. The country's Muslim majority is the target of Islamist radicalization.

During the next two generations, those problems are likely to grow worse if climate change, as predicted, raises sea levels and temperatures.

By 2050, rising oceans are projected to cost the low-lying country 17 to 20 percent of its landmass. That, in turn, is expected to render at least 20 million people homeless and ruin food production of rice and wheat, according to the U.N. Intergovernmental Panel on Climate Change.

The potential for internal unrest to spill into neighboring India is great.

"That is a frightening scenario," said Maj. Gen. A.N.M. Muniruzzaman, a retired Bangladeshi military officer who heads a research center called the Bangladesh Institute of Peace and Security Studies. "Given the complications of conflict relations in South Asia, any destabilization of a regional border can have very severe consequences."

Many Bangladeshis already try to flee to India, either to escape the periodic floods or to seek jobs. The deluge of people is so great that the Indian government has built a border fence - and plans to electrify it.

"We are saying it can go into a meltdown phase unless we have a response mechanism both at the national level and international level in place, rehearsed and solidly put into position so that it can be kicked into action very quickly," Muniruzzaman said of the prospect of major climate change.

U.S. officials have little doubt that climate change could require a major military response. Last summer, the U.S. Navy conducted its first "war game" to assess its ability to respond to possible climate change-related conflicts around the world. The exercise at the Naval War College in Newport, R.I., involved scientists, water specialists, climatologists, aid workers, intelligence officials, business analysts and military officers. The results revealed major gaps in the military's ability to respond, according to a report obtained by the Medill National Security Reporting Project.

The scenarios played out in the war games - one involving West Africa in 2017 and the other set in South Asia from 2010 to 2050 - were "too large in scale, scope and complexity to be adequately addressed given the existing missions and capabilities."

The scenarios combined existing security challenges, such as ethnic strife and Islamic extremism, with climate-related changes, including drought, flood and mass migration. In the context of the scenarios, the report says, the Pentagon had only limited capabilities to provide humanitarian assistance and disaster relief, airlifts, maritime intelligence and port reconstruction.

The Pentagon also lacked cultural expertise and the relationships needed to provide massive assistance in the face of a major disaster, the report says. The exercise suggested that, to be prepared for such a contingency, the Navy would need ships that could provide temporary shelter and use mobile desalinization plants to produce potable water.

"The reality of climate change has forced itself on the U.S. military agenda," said Marc Genest, a professor at the Naval War College who organized the exercise.

A weather-related disaster is a certainty in Bangladesh, regardless of climate change. In 1991, a cyclone killed 140,000 people, though a $10 billion program to build concrete storm shelters has since cut the threat. In 2007, a relatively small number of people - 3,500 - died in Cyclone Sidr after 2 million people were sent to the shelters.

Still, Bangladesh remains a center of concern about climate change. The Coast Guard has given Bangladesh 21 defender class search-and-rescue boats, and it plans to provide three ambulance boats worth a total of $10.5 million.

The U.S. Navy routinely trains with the Bangladeshi military in exercises such as Cope South 2010, which concluded in September, where the two forces exchanged airlift and airdrop delivery techniques to respond better to regional disasters. More exercises are lined up for coming months.

But some say climate change as a national security threat has yet to trickle down to the operational and planning level.

"You may see it come out at a war game in the war college or being discussed in academic circles," said Maj. Luke Donohue, who heads the Office of Defense Cooperation at the U.S. Embassy in Bangladesh's capital, Dhaka. But, he said, "it's not the issue of the day."

- Medill News Service

Nayak is a graduate student at Northwestern University's Medill School of Journalism. This report is part of Medill's National Security Reporting Project, which is overseen by Josh Meyer, a former national security writer for the Los Angeles Times who teaches in Medill's Washington program, and Ellen Shearer, the director of Medill's Washington program.