Hezbollah Is Blamed in Attack on Israeli Tourists in Bulgaria

American officials on Thursday identified the suicide bomber responsible for a deadly attack on Israeli vacationers here as a member of a Hezbollah cell that was operating in Bulgaria and looking for such targets, corroborating Israel’s assertions and making the bombing a new source of tension with Iran.

One senior American official said the current American intelligence assessment was that the bomber, who struck Wednesday, killing five Israelis, had been “acting under broad guidance” to hit Israeli targets when opportunities presented themselves, and that the guidance had been given to Hezbollah, a Lebanese militant group, by Iran, its primary sponsor. Two other American officials confirmed that Hezbollah was behind the bombing, but declined to provide additional details.