The U.S. has added the leader of Hamas to its list of international terrorists, ratcheting up pressure on the Islamic militant group.

State Department counterterror official Nathan A. Sales told a Tel Aviv conference that Ismail Haniyeh is now considered a "specially designated global terrorist." The designation freezes any assets Haniyeh may have in U.S. jurisdictions and bars Americans from any financial transactions with him.

The U.S. already considers Hamas a terrorist organization. Wednesday's announcement steps up U.S. opposition to the group, which has killed hundreds of Israelis and has fought three wars with Israel since taking over the Gaza Strip in 2007.

Hamas says the designation will not deter it from opposing Israel. Other Hamas officials, including the group's Gaza leader, are also on the list.