(JTA) – The United States put twin brothers from South Africa who planned attacks on Jewish institutions in their country and on the U.S. Embassy on its terror blacklist. Brandon-Lee and Tony-Lee Thulsie, 24, were arrested in July 2016 in South Africa and charged with three counts related to terrorism. They had converted to Islam the year before. The State Department said that because of the threat they pose to U.S. security, the pair had been named Specially Designated Global Terrorists. The twins allegedly tried to fly to Syria in April 2015 to join the Islamic State but were stopped after the Hawks, a specialized crime-fighting unit, informed the airline on which they intended to travel. They are subsequently alleged to have “unlawfully and intentionally conspired and attempted to perform acts” that would assist the Islamic State and made themselves available to the terrorist group in order to conduct terrorist activity, the State Department said. The brothers had been under surveillance for about a year before their arrest. Their arrests reportedly were the first in South Africa relating to alleged membership in the Islamic State.