President Donald Trump stood by his national security adviser, Mike Waltz, after The Atlantic’s editor-in-chief was accidentally added to a private, high-level chat on the messaging app Signal where military plans were being discussed. “Michael Waltz has learned a lesson, and he’s a good man,” Trump said Tuesday in a phone interview with NBC News. Trump’s comments were his first substantive remarks since The Atlantic broke the story, which detailed how journalist Jeffrey Goldberg was inadvertently added to a group chat on a private messaging app where plans for military strikes in Yemen were discussed. Goldberg said he was added to the discussion after receiving a request from a user identified as Waltz. When asked what he was told about how Goldberg came to be added to the Signal chat, Trump said, “It was one of Michael’s people on the phone. A staffer had his number on there.”  Trump said Goldberg’s presence in the chat had “no impact at all” on the military operation. The president expressed confidence in his team, saying he was not frustrated by the events leading up to The Atlantic’s story. The situation, Trump said, was “the only glitch in two months, and it turned out not to be a serious one.” The Atlantic’s story sent shockwaves across Washington on Monday. Democratic lawmakers demanded answers from the White House in multiple letters, with one from a group of Senate Democrats calling the situation “an astonishingly cavalier approach to national security.” Top Democrats on the House Armed Services, Intelligence, Foreign Affairs and Oversight committees wrote a separate letter, pushing for answers about other instances in which senior officials discussed national security issues “using the Signal messaging service or any other messaging service application that has not been approved for the transmission of classified information.” White House officials defended the chat, with Defense Secretary Pete Hegseth claiming on Monday that “nobody was texting war plans.” White House press secretary Karoline Leavitt on Tuesday also claimed war plans were not discussed and “no classified material was sent to the thread.” “As the National Security Council stated, the White House is looking into how Goldberg’s number was inadvertently added to the thread,” she added. In a statement about the incident, the National Security Council said the thread “is a demonstration of the deep and thoughtful policy coordination between senior officials. The ongoing success of the Houthi operation demonstrates that there were no threats to our servicemembers or our national security.” Trump and Waltz spoke on Monday about The Atlantic’s story, according to two sources familiar with their conversation. Waltz has not yet commented publicly on the story.  The news of the group chat mishap came 10 years ago to the month after it was revealed that Hillary Clinton used a private email server at times during her tenure as secretary of state in the Obama administration. That revelation prompted staunch criticism from Republicans, several of whom appeared to be part of the Signal chat, according to The Atlantic. Goldberg reported that he was skeptical about the Signal chat’s authenticity at first. But when bombs began falling in Yemen at the time officials in the group chat had discussed it, Goldberg concluded that the chat was “almost certainly real” and left shortly after. Trump briefly responded to a question about The Atlantic’s story on Monday, saying, “I don’t know anything about it” and noting that the reporter asking him about the story was “telling me about it for the first time.” This story first appeared on NBCNews.com. More from NBC News: Job applications surging among DOGE’s targets As Trump and his allies push to impeach judges, Speaker Mike Johnson eyes an escape hatch Trump’s promise of a quick end to Ukraine war gets a reality check after talks end with no deal ...read more read less