Former President Donald Trump challenged a claim by President Joe Biden on Thursday after he said the chairman of the Joint Chiefs of Staff told him climate change was the “greatest threat.”

Trump said in a statement Thursday:

Biden just said that he was told by the Joint Chiefs of Staff that Climate Change is our greatest threat. If that is the case, and they actually said this, he ought to immediately fire the Joint Chiefs of Staff for being incompetent!

Biden a day earlier during a speech to U.S. troops claimed that during a visit to the Pentagon with then-President Barack Obama, the chairman of the Joint Chiefs of Staff told them that climate change was the “greatest threat” facing America.

Biden said at Royal Air Force Mildenhall in the United Kingdom:

You know, when I went over in the Tank in the Pentagon, when I first was 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. And this is not a joke: You know what the Joint Chiefs told us the greatest threat facing America was? Global warming. Because there’ll be significant population movements, fights over land, millions of people leaving places because they’re literally sinking below the sea in Indonesia; because of the fights over what is arable land anymore.

Biden did not give a date for the meeting but according to an NPR article, Obama first visited the Pentagon on January 28, 2009, to receive a briefing on challenges in the world. At the time, the chairman of the Joint Chiefs of Staff was Navy Adm. Mike Mullen, who served in the position from 2007 to 2011.

Also at that time, more than 100,000 U.S. troops were fighting terrorists in Iraq and Afghanistan. U.S. troops would not depart Iraq until the end of 2011, and Obama was struggling on the path forward in Afghanistan. He would later in 2009 call for a surge of tens of thousands of U.S. forces to Afghanistan.

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