Israel notified US before pager attacks but gave no details of plans, sources say

Israeli officials notified the US that the country was going to carry out an operation in Lebanon on Tuesday but did not give any details about what they were planning, according to three sources familiar with the matter, including in a call between Defence Secretary Lloyd Austin and Israeli Defence Minister Yoav Gallant early Tuesday morning.

The fact no details about the operation were given meant US officials were in the dark until reports of hundreds of exploding pagers emerged a short time later, the sources said.

CNN has learned that Israel was behind the audacious attack, which has heightened tensions in a region already on edge even further, and it was a joint operation between Israel's intelligence service, the Mossad and the Israeli military. The Lebanese government condemned the attack as "criminal Israeli aggression."

READ MORE: Lebanon rocked by second wave of exploding devices in 'new phase' of war

At least 20 people were killed and more than 450 were injured, according to health officials in Lebanon, on Wednesday after walkie-talkies detonated in a fresh wave of explosions, one day after the pager blasts killed at least 12 people.

Tuesday's explosions came as Secretary of State Antony Blinken was travelling from Washington to Cairo on Tuesday, stunning US diplomats who watched the breaking news in real-time on their aeroplane TVs.

It wasn't the first time that Israel has taken provocative action around the same time Blinken was on a visit to the Middle East.

But this specific action triggered concerns about regional escalation that the US has long been trying to avoid. Blinken said the US "did not know about nor was it involved in these incidents."

The US conveyed to Iran via a back channel that they were not involved in the attack and that Iran should not escalate, a separate US official told CNN. Iran's ambassador to Lebanon was injured by the exploding pagers, according to Iranian state media. Throughout the course of the nearly year-long war in Gaza, the US has consistently sent indirect messages to Tehran about not escalating.

Gallant and Austin spoke a second time later Tuesday after it became clear thousands of Hezbollah members were wounded by exploding pagers, but officials declined to go into what was discussed.

White House press secretary Karine Jean-Pierre said Tuesday that "the US was not involved" and was "not aware of this incident that hundreds of pagers … were going to explode in Lebanon ahead of time."

Jean-Pierre's wording was precise in that the US was not told about specifically about exploding pagers in advance. The notification from Israel was far more generic and vague, leaving US officials with questions about what the operation could be, the sources said.

Since Hamas' October 7 attack, Israel has regularly carried out strikes in Lebanon in response to the launch of Hezbollah drones and missiles. Israel has also targeted senior Hamas officials in Lebanon. The breadth of Israeli operations in Lebanon over the past 11 months added to the questions about what Israel could be planning.