The two countries have been fighting a shadow war for years. But direct attacks are bringing direct reprisals, or at least plans for them.

They began circulating last week on the Telegram messaging app. Israel has been planning a response to a ballistic-missile barrage carried out by Iran on Oct. 1, Tehran's second direct attack on Israel in six months. Israel has intensified its offensive in Gaza and Lebanon, days after the killing of Hamas leader Yahya Sinwar.

President Joe Biden is "deeply concerned" about a leak of classified documents that contain the US's assessment of Israeli plans to attack Iran, White House National Security Council spokesman John Kirby said. Officials have not determined whether the documents were released due to a hack or a leak, Mr Kirby said.