The U.S. Defense Department has issued a dire report on how climate change could affect the nation’s armed forces and security, warning that rising seas could inundate coastal bases and drought-fueled wildfires could endanger inland ones.

The 22-page assessment delivered to Congress on Thursday says about two-thirds of 79 mission-essential military installations in the U.S. that were reviewed are vulnerable to current or future flooding, with more than half vulnerable to current or future drought. About half also are at risk from wildfires, including the threat of mudslides and erosion from rains following the blazes.

“The effects of a changing climate are a national security issue with potential impacts to DOD missions, operational plans and installations,” Defense Department spokeswoman Heather Babb said in an email.

The report, which was mandated by Congress, describes widespread impacts, dispersed across the U.S., with more coastal flooding along the East coast and Hawaii.

U.S. military facilities are already encountering some of the effects, the Pentagon says, noting that Joint Base Langley-Eustis in Virginia has experienced 14 inches of sea level rise since 1930. And Navy Base Coronado in California already experiences flooding during tropical storm events.

In the Washington area, several Defense Department sites — including Joint Base Andrews, home of Air Force One — are experiencing drought conditions that have been severe the past 16 years, the report says. Those conditions can lead to ruptured utility lines and cracked roads, the Pentagon warns, as moisture disappears from soil.

The Defense Department stresses in its report that it is working with nations around the world “to understand and plan for future potential mission impacts” from climate change, describing it as “a global issue.”

Under the Obama administration, the effects on climate on the nation’s military was a top initiative, but the Trump administration has taken a different tack. In a reversal, climate change was omitted in 2017 as a threat from the National Security Strategy, a list a threats facing the nation.

“Given future global energy demand, much of the developing world will require fossil fuels, as well as other forms of energy, to power their economies and lift their people out of poverty,” the 2017 strategy said. “U.S. leadership is indispensable to countering an anti-growth energy agenda.”

The Obama administration had warned climate change was an “urgent and growing threat to our national security.”