Why Climate Change is a National Security Threat

The U.S. intelligence community published its 2025 annual threat assessment on March 25. Missing from the document was any mention of climate change—marking the first time in over a decade that the topic has not appeared on the list.

"What I focused this annual threat assessment on, and the [Intelligence Committee] focused this threat assessment on, are the most extreme and critical direct threats to our national security," Director of National Intelligence Tulsi Gabbard said in response to questioning on the removal during a Senate Intelligence Committee. 

Gabbard said she “didn’t recall” instructing the intelligence community to avoid mentioning climate change in the report. But the change comes amid the Trump Administration’s continued push for a deprioritization of climate change in the federal agenda. 

Read more: Here Are All of Trump’s Major Moves to Dismantle Climate Action

The U.S. government has considered climate change a global security threat for at least three decades. Academic reports at the Naval War College included environmental stressors and climate change in the 1980s, says Mark Nevitt, associate professor of law at Emory University. On the federal level, climate change was first acknowledged as a national security threat by President George W. Bush in August 1991, and the U.S. national security community first listed the issue as a threat in 2008. 

The issue has typically been included on the annual threat assessment list because of its destabilizing impact—both domestically and abroad. “The annual threat assessment is projecting forward about where the areas of concern and the areas of competition [are], and where the U.S. national security sector should be focusing its attention,” says Nevitt. “Because climate change is just destabilizing different parts of the world, through extreme weather, through droughts, through sea level rise…the intelligence community wants to be ready for future conflicts and future areas of competition.”

Climate change is often referred to as a “threat multiplier” by the intelligence community, because it aggravates already existing problems, while also creating new ones. 

“It takes things that we were already worried about, like extremism or terrorism, and exacerbates the scale or nature of those threats,” says Scott Moore, practice professor of political science, with a focus on climate and security, at the University of Pennsylvania. “If you have these intensified climate change impacts, they place stress on things like food systems, and worsen already existing tensions within countries.”

Climate migration, for example, is on the rise around the world—more than half of new internal displacements within countries registered in 2023 were caused by weather related disasters, according to the Migration Data Portal. 

“Mass migration leads to a lot of political and social tensions as well as border issues,” says Karen Seto, professor of geography and urbanization science at the Yale School of the Environment. “That … could affect national security, because it could destabilize an entire region.” One study from the journal Proceedings of the National Academy of Sciences found that extreme weather is contributing to migration into the United States through the southern border—with more migrants from agricultural regions in Mexico settling in the United States following extreme drought. 

Such displacement can have major impacts on people's lives and livelihoods, experts say—especially in already fragile regions. “If you have, for example, a really extreme and intensified drought in a country in which extremist ideologies are percolating, these climate change impacts may make it more likely that people are going to stop farming, or might migrate to cities where they may face difficult employment prospects, be socially dislocated and may be more vulnerable to extremism or engaging in some type of violence,” says Moore.   

On a domestic level, considering climate change helps the U.S. military ensure that infrastructure is built to withstand extreme weather events—and respond to national disasters both domestically and abroad. “You need the National Guard, the Coast Guard, the U.S. military, to basically help out their community when there's an extreme weather event,” says Nevitt. As extreme weather events intensify with climate change this could strain military resources and put more lives at risk if the military does not prepare to address the threat.

Infrastructure within the U.S., like energy and internet grids, also need to be fortified. If regions were to lose power in the case of an extreme weather event, the networks could be vulnerable to attack. 

“Our energy grid is highly at risk, and we've seen wildfires happening across the country, and so these could again be threat multipliers," says Seto. “I think the national security risk is that we are not ready to respond to any threats from foreign agents that may take advantage of the weaknesses that we might have.”

Showing that the climate crisis is a priority is also necessary to maintain the United States’s diplomatic strength—especially in regions that see climate change as a top concern. “Other countries, in particular countries that are very significant for the U.S. defense posture, like the Pacific Island countries, really care about climate change a lot. They want to hear what the United States is willing to do to help them deal with climate change,” says Moore. “And so when you have the instructions to essentially ignore climate change, or in an extreme version almost censor mention of climate change, that's going to have a harmful effect on diplomatic engagement with some pretty important countries.”