Mike Waltz has said he is “embarrassed” after leaking top-secret war plans to a journalist.

The US national security adviser said he took “full responsibility” for the incident, which saw sensitive details about US military strikes on Yemen sent to Jeffrey Goldberg, editor-in-chief of The Atlantic.

“[It’s] embarrassing, yes,” he told Fox News’ Laura Ingraham on Tuesday evening.

He continued: “We made a mistake, we’re moving forward and we’re going to continue to knock it out of the park for this President.”

Asked by Ms Ingraham if an aide was responsible for the security breach, Mr Waltz answered:  “A staffer wasn’t responsible. And look, I take full responsibility. I built the group,” referring to the chat on the messaging app Signal.