This story was originally published by Mother Jones and is reproduced here as part of the Climate Desk collaboration.

With a major global climate summit in Paris less than two weeks away, the Obama administration’s top environmental official is saying that climate change is a major threat to U.S. national security.

“There are a variety of impacts that we’re feeling from a changing climate, and we need to stop those impacts from escalating by failing to take action — one of those is instability,” said Gina McCarthy, administrator of the Environmental Protection Agency, in an interview Tuesday with Climate Desk. McCarthy pointed to drought and wildfires in California as examples of climate impacts that can displace people from their homes, and she noted that many of the same things are happening in less stable parts of the world. You can watch portions of the interview above.

“We can see that underlying issues in many countries that lead to animosity, and then can lead to conflict,” she said. “So it is a national security issue for us, as well as an issue that’s incredibly important for our local communities.”

McCarthy’s comments join a growing chorus of experts who see a direct link between global warming and national security. The debate over that theory seems likely to intensify over the next few weeks, in part because the Paris climate negotiations follow closely on the heels of Friday’s terrorist attacks that left 129 people dead in the French capital.

Just days before the Paris attacks, Secretary of State John Kerry gave a speech in which he called climate change “a threat to the security of the United States.” On Saturday, Democratic presidential contender Bernie Sanders said that “climate change is directly related to the growth of terrorism.” President Barack Obama has made a similar point several times, as have numerous security experts and defense officials. (Donald Trump is skeptical.)

After the attacks, French officials were quick to confirm that the climate summit — which is meant to yield a groundbreaking international agreement to slow climate change — would go on, albeit with scaled-back public events and heightened security. President Obama is expected to attend, along with White House negotiators. McCarthy has not yet said whether she will be there, and while her agency isn’t responsible for conducting the core negotiations, she still has a vital role to play in convincing other countries that the United States is serious about climate action.

The U.S. negotiating position — Obama has promised to cut greenhouse gas emissions 26 to 28 percent below 2005 levels by 2025 — hinges largely on the Clean Power Plan, a new set of EPA regulations on emissions from power plants that was largely crafted under McCarthy. The plan itself cites national security as a justification for taking action on global warming. “Impacts of climate change on public welfare also include threats to social and ecosystem services … these impacts are global and may exacerbate problems outside the U.S. that raise humanitarian, trade, and national security issues for the U.S.,” it states.

The EPA plan has come under heavy fire since the Clean Power Plan was finalized in August. A coalition of two dozen coal-dependent states are attempting to block the plan in court, and on Tuesday, the Senate passed a pair of resolutions to overturn the plan. Those resolutions face a certain veto from Obama.

McCarthy said she is “very confident” the plan will survive all these challenges. But since it forms the legal basis for the U.S. commitment in Paris, McCarthy said her staff has been in contact with their counterparts in other countries in an effort to assure them that they can count on the U.S. to follow through.

“We’re moving forward, and we try to make people understand that,” McCarthy said. The Clean Power Plan is “a signal of the seriousness of the United States and this president, and the fact that we are going to be driving reductions down that other countries can count on, so they can come to the table and also contribute.”