BREAKING: Biden tells troops 'global warming' is the 'greatest threat to America'

President Joe Biden spoke to troops at the US Air Force Base in Suffolk, England, on Wednesday, at the beginning of his first overseas trip as president. Even so, he joked "I keep forgetting I'm president."

Biden told the troops about the "toughest challenges and the issues that matter most to our future." He said "we're committed to leading with strength and leading with our values."

The biggest of these challenges, Biden said, are climate change. "We must all commit to an ambitious climate action if we're going to prevent the worst impacts of climate change, limiting global warning—warming—to no more than 1.5 degrees Celsius," he said.

"We need the global transition to clean energy technology. Y'know when I was over in the tank in the Pentagon, and I was first elected vice president with President Obama, the military sat us down to let us know what the greatest threats facing America were, the greatest physical threats.

"This is not a joke. Y'know what the Joint Chiefs told us the greatest threat facing America was?

"Global warming," Biden said.

"Because there'll be significant population movements, fights over land, millions of people leaving places because they are literally sinking below the sea in Indonesia. Because of the fights over what is arable land anymore," the president said.

Climate change is one of Biden's four signature crises that he rode into the White House. The others are the economy, the coronavirus, and systemic racism. Vice President Kamala Harris has also said that climate change is one of the "root causes" of the border crisis.