U.S. officials are extremely concerned about a potentially major security breach after two alleged U.S. intelligence documents about Israel's preparations for an attack on Iran were published by a Telegram account affiliated with Iran. Why it matters: The alleged leak comes as Israel completes weeks of preparations for a retaliation against Iran, which attacked Israel with a barrage of ballistic missiles on Oct. 1. • The leak could be an attempt to disrupt the Israeli operation. • The Pentagon...