Top national security officials for US President Donald Trump, including his defence secretary, texted war plans for upcoming military strikes in Yemen to a group chat in a secure messaging app that included the editor-in-chief for The Atlantic, the magazine reported in a story posted online on Monday.

The National Security Council said the text chain “appears to be authentic”. Trump initially told reporters he was not aware that the highly sensitive information had been shared two and a half hours after it was reported. He later appeared to joke about the breach.