WASHINGTON - The US Treasury sanctioned the leader of the Lebanese terrorist group and political movement Hezbollah on Thursday for helping Syria crush anti-government protests, as well as two other members for the group's "terrorist activities" in general.Sanctions experts described the move against Hezbollah Secretary-General Sayyed Hassan Nasrallah as largely symbolic because the penalties - freezing any assets he holds in US banks - had been imposed under earlier US sanctions.Saying Hezbollah had long been supported by the Assad government, the Treasury Department said the militant group "is now returning the favor by providing training, advice and extensive logistical support .... as the Assad regime continues to wreak havoc on the Syrian people through the use of terror and violence - Hezbollah's area of expertise."Asked about the effect of the Treasury's action against Nasrallah, sanctions lawyer Douglas Jacobson said: "In reality, it's symbolic. It's simply piling on to include an additional designation for his alleged role with respect to Syria."While acknowledging the latest sanctions impose penalties similar to those already on Nasrallah since 1995 and 2001, a Treasury official said the government took the step "to bring to the attention of the international community his egregious involvement, and that of Hezbollah, in the Syrian conflict."The official, who spoke on condition of anonymity, said the two other men designated on Thursday had not been previously targeted under US executive orders or laws.The Treasury said it had "designated" Nasrallah under US Executive Order 13582, signed by US President Barack Obama in August 2011 in part to crack down on those helping Syria repress the uprising against Syrian President Bashar Assad's rule.More than 27,000 people are believed to have died in the 17-month-old conflict.The Treasury also said it sanctioned two other Hezbollah members: Mustafa Amine Badreddine, who has been accused by a UN tribunal in the 2005 killing of former Lebanese Prime Minister Rafik al-Hariri, and a man it identified as Talal Hamiya, the head of Hezbollah's external security organization.Those two were targeted under Executive Order 13224 "for providing support to Hezbollah's terrorist activities in the Middle East and around the world," the Treasury Department said in a written statement.That executive order also freezes the targets' assets that fall under US jurisdiction."By aiding Assad's violent campaign against the Syrian people and working to support a regime that will inevitably fall, Hezbollah's ongoing activity undermines regional stability and poses a direct threat to Lebanon's security," Undersecretary of the Treasury David Cohen said in the statement."Hezbollah's actions ... clearly reveal its true nature as a terrorist and criminal organization," he added.