The Trump administration’s first National Defense Strategy, which was released last Friday, outlines the U.S. Department of Defense’s national security goals in a world it describes as rife with great power competition between the United States, Russia, and China. Climate change – which some military leaders warn poses a looming threat to the effectiveness of American military power – was not mentioned, in stark contrast to the previous administration’s strategic priorities. National security and defense strategies issued by the Obama Administration highlighted the dangers climate change poses to national security, including “increased national disasters, refugee flows, and conflicts over basic resources like food and water.”

The omission also contrasts with recent comments from Defense Secretary Mattis and other leading defense officials in this administration: “Climate change is impacting stability in areas of the world where our troops are operating today,” wrote Mattis in testimony provided to the Senate Armed Services Committee. He recommended the military consider how changes like open-water routes in the thawing Arctic and drought in global trouble spots will impact its operations and readiness.

But the Pentagon will likely continue to recognize and prepare for the effects of climate change. The 2014 Climate Change Adaptation Roadmap, a policy paper outlining the areas of instability caused by extreme weather events like hurricanes and flooding, guides the Pentagon’s preventative actions. In addition, the bipartisan Langevin Amendment to the 2018 National Defense Authorization Act requires the Department of Defense to assess military vulnerabilities due to climate change and provide recommendations for the next 20 years.

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The national security implications of climate change affect U.S. military operations at home and around the globe: Weather and terrain are key to the Department of Defense’s planning, so rapid environmental changes have severe consequences. Rising sea levels affect military infrastructure, such as the naval base in Norfolk, Virginia, and operations in areas like the Arctic, which is gaining geostrategic importance as it warms.  As “disaster alleys” in the Asia-Pacific region are battered by more frequent and more severe storms, the U.S. military is increasingly called upon to respond.

Climate change is already exacerbating instability in climate-conflict hotspots: Specific hotspots—places that are environmentally vulnerable and politically unstable – may pose unique and unpredictable security threats to the United States. Examples include “disputes over the Nile River, increased piracy in Somalia, and food instability in the Sahel,” said General Paul J. Selva, the vice chairman of the Joint Chiefs of Staff, in his recent testimony to Congress.

Senior military leaders have consistently warned about the security risks of climate change: Since 2004, every U.S. Secretary of Defense has publicly noted that climate change will pose challenges to the military and guided the department to prepare for these impacts. Past and current military leaders have described climate change as a “threat multiplier,” a term coined by Wilson Center Senior Fellow and former defense official Sherri Goodman. And Congress has recently found common ground on this issue, garnering bipartisan support for defense efforts to assess and prepare for climate change.