TORONTO - Some of the world's most powerful nations are getting increasingly desperate for fresh water and observers are concerned that a day will come when countries will fight for the dwindling resource.

Countries in the Middle East and Africa have long dealt with water shortages but now the likes of China, India and the United States are grappling with the problem.

And the United Nations says five billion people will be living in areas with limited water availability by 2025, which will only exacerbate tensions and demand for the limited supply.

Water management has been pushed to the top of the political agenda in some countries and military leaders are now being drawn into long-term planning to help strategize how governments will face their dry futures.

Climate change and subsequent consequences like water scarcity present a serious threat to national security, said a panel of 11 retired three-star and four-star American admirals and generals in a recent report for the CNA Corp., a non-profit organization.

While it's not yet expected that water will be the sole cause of a war, the report suggests a fight over natural resources could be the final straw that pushes countries into conflict.

"Disputes over key resources such as water do not automatically trigger violent outcomes, and no recent wars have been waged solely over water resources," the report states.

"Nevertheless, resource scarcity always has the potential to be a contributing factor to conflict and instability in areas with weak and weakly-supported governments. In addition, there is always the potential for regional fighting to spread to a national or international scale."

No expert is suggesting that Canadians should begin to worry about being targeted for their water, but at the very least, tensions could arise with the United States if disagreements develop over water policies, said Achim Steiner, executive director of the United Nations Environment Program, in a statement earlier this year.

"Canada and the United States are, despite being strong economies with the financial power to cope, facing many of the same impacts that are projected for the rest of the world," he wrote.

"The impacts could be acute and may require very careful, strategic planning and investment if tensions are to be avoided between humans and nature, and between a wide-range of economically and socially-important water users."

Maude Barlow of the Council of Canadians said she doesn't doubt the Americans would try to pressure Canada into sharing its water in a time of crisis.

"I am absolutely convinced that the United States has already targeted Canada's water, I'm absolutely convinced there are high-level conversations going on between some people in government and business in our country and the United States," she said.

The Great Lakes probably wouldn't be targeted but she predicted interests could turn to the North once demand for water gets serious.

"My thinking is (Americans are interested) in those mighty rivers in Canada's North and the intention eventually is to build big pipelines to reverse the flow of that water (south)," she said.