When Pakistan warned in April 2025 that attempts to stop or divert its treaty-protected water supplies would constitute an “act of war,” it identified a danger that extends far beyond its rivalry with India. A government that believes another country can control its access to water may eventually conclude that defending its people requires military force.
Future wars will be fought over who controls the water that sustains national economies and human life. Some may begin with deliberate restrictions, while others could emerge from fear that a neighboring government is acquiring the ability to impose them. Understanding that distinction is essential to preventing a dispute over a river from becoming a war across a border.
While studying at the U.S. Naval War College in 2020, I examined this danger along the Mekong River. My research explored how China’s upstream dams could give Beijing leverage over downstream countries whose livelihoods depend on water flowing from Chinese territory. The central concern was that control over a shared resource could become control over another nation’s choices.
Research published since then reinforces the physical basis of that concern. A 2024 study found that dams across the Mekong basin had shifted as much as 20 percent of the mainstream’s annual water volume between wet and dry seasons in recent years. Annual totals alone therefore cannot capture what downstream communities experience. Water arriving outside a planting season or failing to sustain a seasonal flood can have consequences even when it eventually reaches the same destination.
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