US President Donald Trump announced the strikes on March 15, but The Atlantic magazine’s editor-in-chief Jeffrey Goldberg wrote on Monday that he had hours of advance notice via the group chat on Signal, which included Defense Secretary Pete Hegseth and Vice President JD Vance.

Top Democrats were quick to condemn the breach, saying it was potentially illegal and calling for an investigation to find out how it happened, while Republicans tried to play down the incident.

“The message thread that was reported appears to be authentic, and we are reviewing how an inadvertent number was added to the chain,” National Security Council spokesman Brian Hughes said.

The White House said Trump “continues to have the utmost confidence in his national security team,” after the US president earlier said he did not “know anything about” the issue.

Hegseth, a former Fox News host with no experience running a huge organization like the Pentagon, took no responsibility for the security breach as he spoke to reporters late Monday.

He instead attacked Goldberg and insisted that “nobody was texting war plans,” despite the White House confirming the breach.

Goldberg wrote that Hegseth sent information on the strikes, including on “targets, weapons the US would be deploying, and attack sequencing,” to the group chat.

“According to the lengthy Hegseth text, the first detonations in Yemen would be felt two hours hence, at 1:45 pm eastern time,” Goldberg wrote — a timeline that was borne out on the ground in Yemen.

The leak could have been highly damaging if Goldberg had publicized details of the plan in advance, but he did not do so.

The journalist said he was added to the group chat two days earlier, and received messages from other top government officials designating representatives who would work on the issue.

On March 14, a person identified as Vance expressed doubts about carrying out the strikes, saying he hated “bailing Europe out again,” as countries there were more affected by Huthi attacks on shipping than the United States.

‘Dangerous’

Group chat contributors identified as National Security Advisor Mike Waltz and Hegseth both sent messages arguing only Washington had the capability to carry out the strikes, with the latter official saying he shared Vance’s “loathing of European free-loading.”

As he spoke to reporters Monday Hegseth dodged questions about the leak, in which highly sensitive material was also shared on a commercial app rather than in secure military channels reserved for such communications.

The security breach provoked outrage among Democrats, including some like Senator Elizabeth Warren who said the exchange over group chat could be illegal.

Senate Minority Leader Chuck Schumer described it as “one of the most stunning breaches of military intelligence I have read about” and called for a full investigation.

And Hillary Clinton — who was repeatedly attacked by Trump for using a private email server while she was secretary of state — posted on X: “You have got to be kidding me.”

The reaction of top Republicans like House Speaker Mike Johnson was less critical.

Johnson said those involved should not be punished, calling it a “mistake” that “won’t happen again”, news site Axios reported.

But former national security officials reacted with shock.

“Some of these issues… they should only be discussed face to face,” former national security advisor John Bolton told CNN.

“I have no faith that the Department of Justice will prosecute anyone involved.”

Huthi attacks

The Huthi rebels, who have controlled much of Yemen for more than a decade, are part of the “axis of resistance” of pro-Iran groups staunchly opposed to Israel and the United States.

They have launched scores of drone and missile attacks at ships passing Yemen in the Red Sea and Gulf of Aden during the Gaza war, saying they were carried out in solidarity with Palestinians.

The Huthis’ campaign crippled the vital route, which normally carries about 12 percent of world shipping traffic.

The US began targeting the Huthis in response under the previous administration of president Joe Biden, and has launched repeated rounds of strikes on Huthi targets, some with British support.

Trump has vowed to “use overwhelming lethal force until we have achieved our objective,” citing the Huthis’ threats against Red Sea shipping.