Senate Democratic leader Chuck Schumer called for a "full investigation" after The Atlantic reported top national security officials for President Donald Trump texted war plans for upcoming military strikes in Yemen to a group chat in a secure messaging app that included the editor-in-chief of the magazine. The National Security Council said the text chain “appears to be authentic.” Trump initially told reporters he was not aware that the highly sensitive information had been shared, 2 1/2 hours after it was reported. He later appeared to joke about the breach. “This is one of the most stunning breaches of military intelligence I have read about in a very, very long time,” Schumer, a New York Democrat, said in a floor speech Monday afternoon. "If these detailed exchanges about coordinating military operations fell into the hands of America's enemies, it could get people killed. It could severely harm our military. It would put America's national security in danger," he added. The material in the text chain “contained operational details of forthcoming strikes on Iran-backed Houthi-rebels in Yemen, including information about targets, weapons the U.S. would be deploying, and attack sequencing,” The Atlantic editor-in-chief Jeffrey Goldberg reported. It was not immediately clear if the specifics of the military operation were classified, but they often are and at the least are kept secure to protect service members and operational security. The U.S. has conducted airstrikes against the Houthis since the militant group began targeting commercial and military vessels in the Red Sea in November 2023. Just two hours after Goldberg received the details of the attack on March 15, the U.S. began launching a series of airstrikes against Houthi targets in Yemen. The National Security Council said in a statement that it was looking into how a journalist’s number was added to the chain in the Signal group chat. In addition to Defense Secretary Pete Hegseth, it included Vice President JD Vance, Secretary of State Marco Rubio and Tulsi Gabbard, Trump's director of national intelligence. Goldberg said he received the Signal invitation from Mike Waltz, Trump's national security adviser, who was also in the group chat. Hegseth in his first comments on the matter attacked Goldberg as “deceitful” and a “discredited so-called journalist” while alluding to previous critical reporting of Trump from the publication. He did not shed light on why Signal was being used to discuss the sensitive operation or how Goldberg ended up on the message chain. “Nobody was texting war plans and that’s all I have to say about that,” Hegseth said in an exchange with reporters after landing in Hawaii on Monday as he began his first trip to the Indo-Pacific as defense secretary. In a statement late Monday, White House spokeswoman Karoline Leavitt said the president still has the “utmost confidence” in Waltz and the national security team. Earlier Monday, Trump told reporters: “I don’t know anything about it. You’re telling me about it for the first time.” He added that The Atlantic was “not much of a magazine.”