Democratic presidential candidate Bernie Sanders on Sunday defended his comments during the 2nd Democratic presidential debate, Saturday night, that climate change is connected and a lead to active terrorism.

“If we are going to see an increase in drought and flooding and extreme weather disturbances as a result of climate change, what that means is that peoples all over the world are going to be fighting over limited natural resources,” Sanders told CBS News’ host John Dickerson on Face the Nation Sunday morning. “If there is not enough water, if there is not enough land to grow your crops, then you’re going to see migrations of people fighting over land that will sustain them. And that will lead to international conflicts.”

During the Democratic presidential debate on Saturday night, Dickerson asked Sanders if he still believes climate change is the U.S. greatest national security threat in the wake of the horrific terrorist attacks in Paris Friday night.

“Absolutely,” he responded. “In fact, climate change is directly related to the growth of terrorism. And if we do not get our act together and listen to what the scientists say, you’re going to see countries all over the world — this is what the CIA says — they’re going to be struggling over limited amounts of water, limited amounts of land to grow their crops, and you’re going to see all kinds of international conflict.”

On Sunday, Sanders doubled down on his claim, suggesting that the “huge planetary crisis” is the cause of the chaos unfolding in Syria. “What happens, say, in Syria, is that, when you have drought, when people can’t grow their crops, they’re going to migrate into cities. And when people migrate into cities, and they don’t have jobs, there’s going to be a lot more instability, a lot more unemployment. And people will be subject to the types of propaganda that al Qaeda and ISIS are using right now,” he asserted. “So, where you have discontent, where you have instability, that’s where problems arise. And, certainly, without a doubt, climate change will lead to that.”