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

Bernie Sanders opened Saturday night’s Democratic debate by vowing to rid the world of ISIS, the terrorist organization that claimed responsibility for killing more than 100 people in Paris on Friday. In a follow-up question, moderator John Dickerson pointed out that during a debate last month, Sanders had identified “climate change” as the greatest threat to national security. “Do you still believe that?” asked Dickerson.

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“Absolutely,” replied Sanders. He added that “of course international terrorism is a major issue that we have got to address today,” but argued that “climate change is directly related to the growth of terrorism.” Sanders warned that global warming could cause international conflicts “over limited amounts of water, limited amounts of land to grow their crops.” You can watch the full exchange above.

Sanders isn’t alone in arguing that climate change has the potential to make international conflicts worse. According to Director of National Intelligence James Clapper, “Extreme weather, climate change, and public policies that affect food and water supplies will probably create or exacerbate humanitarian crises and instability risks.” The Department of Defense says that climate change “poses immediate risks to U.S. national security” and has the potential to exacerbate terrorism. There’s also substantial evidence that drought linked to climate change helped spark Syria’s civil war.