The lives of British servicemen and women have not been put at risk by a major security breach in the United States, the UK armed forces minister has told MPs.
Luke Pollard said he had “high confidence” that British operational security remains “intact”.
It comes after after a US journalist was inadvertently added to a secret group chat where senior US officials discussed plans for a strike against the Houthi group in Yemen.
The UK did not participate in the recent US strikes against Houthi targets but it did provide routine air-to-air refuelling support for the US.
Asked whether UK personnel had been put at risk by the use of messaging app Signal to discuss US plans for a strike on Yemen, Pollard told the Commons Defence Committee: “No. All UK service personnel are covered by our normal approach to operational security, and the committee will understand that I won’t go into the details of how we keep our involvement in any support for military operations in the Red Sea or anywhere else [secure].
“But we’ve got high confidence that the measures that we have got with our allies, including the United States, remain intact.”
Liberal Democrat leader Sir Ed Davey said the US leak showed that “Trump’s White House can’t be trusted to take even the most basic steps to keep its own intelligence safe”.
He added: “Their fly-by-the-seat-of-your-pants approach to security means it could only be a matter of time until our own intelligence shared with them is also leaked. This could put British lives at risk.
“As a matter of urgency, the government must comprehensively review our intelligence-sharing arrangements with the US.”
The US air strikes against the Houthi militant group in Yemen on 15 March came after continued attacks on shipping in the Red Sea.
But shortly beforehand details of the attack were sent to a Signal group chat that included the US Vice-President JD Vance, Defence Secretary Pete Hegseth and Secretary of State Marco Rubio, among others.
In the chat, Vance seemingly says he hates “bailing Europe out again”, while Hegseth apparently replies to the US vice-president with: “I fully share your loathing of European free-loading. It’s PATHETIC”.
Signal chats are encrypted, but are not approved by the US government for discussion of classified material.
The use of the app to provide details of the airstrikes came to light because one participant had accidentally added the editor-in-chief of the Atlantic magazine, Jeffrey Goldberg, to the group.
Mr Goldberg said he had seen classified military plans for US strikes on Houthi rebels, including weapons packages, targets and timing, two hours before the bombs struck.
Pollard suggested people would face disciplinary proceedings in the UK for a similar breach of operational security – but he stressed he would not comment on the US situation.
“The Ministry of Defence has very clear policies in relation to what information can be shared and the format in which it can be shared. We don’t comment on how allies share their information,” he told the defence committee.
He added: “I’m confident that we have robust measures to safeguard our information and our data, but we also have a very clear set of systems where individuals don’t follow procedures, with sufficient consequences to reflect the actions that have been taken.”
Pollard said there would be “a clear consequence and disciplinary process for anyone that was not following those procedures”.
On Monday night, US president Donald Trump denied any knowledge of the breach, while a White House spokeswoman said the president retained “utmost confidence” in his national security team.