After the bombing, Israel sent investigators to Argentina to search for clues. They learned that the bombers planned the attack in the Tri-Border area, where the borders of Argentina, Paraguay, and Brazil meet and which has a large Muslim population. Messages intercepted by the American National Security Agency revealed Iranian knowledge of the impending attack, as well as the complicity of Hezbollah operative Imad Mughniyah. In fact, Mughniyah was formally charged by Argentina with participating in the bombings of the Israeli embassy.