More Republicans call for investigation of Trump officials' Signal chat

Republican calls to investigate a group chat in which White House national security officials shared sensitive military information has intensified, with Oklahoma Senator James Lankford saying it is "entirely appropriate".

Lankford stopped short of calling for officials to resign when speaking to CNN on Sunday, but he joins a growing number of Republicans who have broken with President Donald Trump over the chat.

The Trump administration has downplayed the unclassified Signal messages in which Defence Secretary Pete Hegseth and others shared potentially classified details about an upcoming attack on Yemen.

Many Democrats have demanded that Hegseth and other officials resign over the incident.

In calling for a investigation, Lankford joins fellow Republican and Senate Armed Services Chair Roger Wicker, who penned a letter earlier in the week requesting the Inspector General of the US Department of Defense look into the incident.

The letter said the discussion of sensitive military information on Signal, an online messaging application, with a journalist present in the chat "raises questions as to the use of unclassified networks to discuss sensitive and classified information".

National Security Advisor Mike Waltz appears to have accidentally added The Atlantic's editor-in-chief, Jeffrey Goldberg, to the chat before the officials discussed the upcoming strikes.

On Sunday, Republican senator Lankford said an independent investigation is warranted to answer some lingering questions about the chat.

"One is obviously, how did a reporter get into this thread in the conversation?" Lankford asked.

"And the second part of the conversation is when individuals from the administration are not sitting at their desk in a classified setting on a classified computer, how do they communicate to each other?"

But Lankford said calls for Hegseth to resign over the issue are "overkill".

"I think he just joined an encrypted app," he said. "I don't see it as much of an issue because, again, they all believed that this was a closed circle of conversation."

"I don't see this as an issue of leadership," Lankford added.

Lankford and Wicker are one of a few Republican lawmakers who have called for an investigation.

The Atlantic first reported details of the group chat on the platform Signal after its Mr Goldberg was added to it by Waltz. He followed the thread as top Trump administration officials discussed upcoming military strikes against the Houthis in Yemen.

The Atlantic then on Wednesday published the entire text thread that showed the detailed and potentially classified rundown for a March air raids.

In the wake of the controversy, Waltz said he took full responsibility for the group chat. "I built the group," he told Fox News on Tuesday, adding it was "embarrassing".

Waltz was unable to explain in his Fox News interview how Goldberg came to be on the chat but said another, unnamed contact of his was supposed to be there in Goldberg's place.

"I can tell you for 100% I don't know this guy," Waltz said.

On Sunday, Goldberg said on NBC's Meet the Press that Waltz is "telling everyone that he's never met me or spoken to me - that's simply not true".

President Trump called the incident a "glitch" and said that it had "no impact at all" operationally, adding that the military strike against the Houthis was a success.

But former national security officials have raised concerns that allowing this to slide could pose major risks and encourage American adversaries.

Sue Gordon, a former Trump administration deputy director of national intelligence, told BBC's US partner CBS News that she was "glad the operation was successful. Now we need to deal with the fact that this should not have happened".

"I don't think we should rest on the fact that nothing bad happened this time," she said. "We don't know whether that communications path has been penetrated. So we don't know whether the state actors that have lots of resources are just sitting and working now."

Those concerns have led many Democrats to call for greater accountability, with Mark Warner, the vice chair of the Senate Intelligence Committee, asserting that if a military officer or CIA agent treated classified information in a similar manner they "would be fired - end of story".

"I believe Secretary Hegseth should resign or be fired. I think Mike Waltz should resign or be fired," Warner told CBS News on Sunday. "If no action is taken, what message does that send to the workforce?"

Still, in an interview with NBC News on Saturday, Trump said he would not fire anyone involved in the group chat, and that he still had confidence in Waltz.

"I don't fire people because of fake news and because of witch hunts," he said.

Along with Waltz and Hegseth, the chat also included Vice-President JD Vance, director of national intelligence Tulsi Gabbard, CIA director John Ratcliffe White House chief of staff Susie Wiles and other senior leaders.