US government officials investigating the leak of two classified intelligence papers assessing Israel’s plans to attack Iran have said they did not believe any more documents had been compromised.
However, the Biden administration remained “deeply disturbed” by the unauthorized release, John Kirby, the national security communications adviser, told reporters at a White House briefing on Monday.
Kirby also said that US officials have spoken with Israeli counterparts about the leak, but he did not divulge details of the conversation.
“We’re deeply concerned, and the president remains deeply concerned, about any leakage of classified information into the public domain. That’s not supposed to happen, and it’s unacceptable when it does,” he said.
“He will be actively monitoring the progress of the investigative effort to figure out how this happened, and obviously he’ll be very interested in hearing any mitigation measures and recommendations that come as a result of the investigative efforts.”
Earlier on Monday, a defense department official confirmed to the Guardian that an in-depth inquiry was under way into how the two documents, attributed to the US Geospatial-Intelligence Agency and National Security Agency, came to be published on the Telegram messaging app four days ago.
The papers relate to Israel’s military planning for a retaliatory strike on Iran following the 1 October missile barrage that was Tehran’s largest-ever assault on its regional foe and an escalation of the Middle East conflict sparked by the Hamas terrorist attacks on Israel in October 2023.
The first document is titled “Israel: air force continues preparations for strike on Iran and conducts a second large-force employment exercise” and the second is “Israel: defense forces continue key munitions preparations and covert UAV activity almost certainly for a strike on Iran”.
Kirby said it was not yet known if the papers, both marked top secret, were deliberately released, or if their publication was the result of a hack. But, he said: “We don’t have any indication at this point that there’s an expectation that there will be additional documents like this finding their way into the public domain.”
Kirby’s update came a day after Mike Johnson, the Republican House speaker, called the leak “very concerning”, and said he was expecting a briefing later on Sunday about the progress of the investigation.
“There’s some serious allegations being made there. We’re following it closely,” the Louisiana congressman said in remarks to CNN’s State of the Union program.
The investigation comes as Antony Blinken, the US secretary of state, was heading to the Middle East on Monday for his 11th visit since the Hamas attacks. As well as discussing the leak, Blinken will try to kick-start ceasefire negotiations stalled since Israel’s killing of the Hamas leader, Yahya Sinwar, last week.
Kirby, however, was cautious about the likely success of Blinken’s mission. “I cannot sit here today and tell you that that negotiations are about to restart in Doha or Cairo or anywhere else for that matter,” he said.
“[We will] continue to engage in intensive diplomacy to see what can be done to try to find a path to a ceasefire between Israel and Hezbollah.”
