In a post on Twitter the State Department's Bureau of Counterterrorism said Safieddine's designation marked the "first ever" joint designation by the State Department and another country.
Safieddine is a key member of Hezbollah's executive council, according to the State Department.
The Trump administration imposed its first terrorism sanctions jointly with Saudi Arabia today as President Donald Trump travels to the kingdom on his first overseas trip.
"The Saudi government today designated a leader of Hezbollah, whose name is Hashem Safieddine", Saudi state news agency SPA said. The Kingdom of Saudi Arabia designated Safieddine under its Law of Terrorism Crimes and Financing and Royal Decree A/44.
As long as Hizballah spreads instability, conducts terrorist attacks and engages in criminal and illicit activities around the world, we will continue to designate Hezbollah's operatives, leaders and businesses, impose sanctions as a result of designation, and disrupt its radical activities.
Saudi Arabia joined the U.S.in targeting Safieddine, who is said to oversee the financial empire of the Lebanon-based party. The Saudis also accuse Iran and Hezbollah of fanning the war in Yemen by supporting the Houthi rebels. The State Department amended the group's FTO designation to include ISIS' affiliate in the Sinai on September 30, 2015.
"The Department of State has designated Hashem Safieddine and Muhammad al-Isawi as Specially Designated Global Terrorists... which imposes sanctions on foreign persons who have committed, or pose a serious risk of committing, acts of terrorism that threaten the security of U.S. nationals or the national security, foreign policy, or economy of the United States", the release stated.
Hezbollah, which has members in Lebanon's parliament and Cabinet, is considered a terrorist organization by the USA government. Moreover, designations can assist or complement the law enforcement actions of other US agencies and other governments.