President Trump made “a serious mistake” in withdrawing from the Iran nuclear deal, former President Barack Obama said in an extended defense of his signature foreign policy agreement.

“[T]he decision to put the JCPOA at risk without any Iranian violation of the deal is a serious mistake,” Obama said, using the acronym for the deal, known formally as the Joint Comprehensive Plan of Action. “Without the JCPOA, the United States could eventually be left with a losing choice between a nuclear-armed Iran or another war in the Middle East.