The U.S. terrorism blacklist has a new member: a Greek group that claims responsibility for two targeted killings.

The designation by Secretary of State Hillary Clinton on Thursday bars Americans from doing business with the Sect of Revolutionaries and freezes any U.S. assets the organization may have.

The group has claimed responsibility for killing an anti-terrorism police officer and a journalist since emerging after 2008 riots that broke out when Greek police fatally shot a teenager. Both of the sect's victims were shot more than a dozen times. The group also took responsibility for attacks on police and a TV station.

"The organization's indiscriminate terrorist activities threaten the national security of the United States," the department said in a statement.

Daniel Benjamin, the department's counterterrorism coordinator, said the move highlights the U.S. government's concern over terrorism in Europe and "demonstrates the U.S. government's support for Greece's efforts to disrupt, dismantle, and defeat this group."

The U.S. says the organization tries to use violence to try to provoke a revolution and overthrow the Greek government.

Militant groups have been active in Greece for decades. Previous organizations sought to portray themselves as urban revolutionaries fighting for the oppressed and legacies of the resistance to the 1967-74 military dictatorship.

Greek authorities contend the Sect of Revolutionaries has a background of common crime rather than political violence. Some analysts have expressed alarm over what they say is the group's lack of clear ideology and its propensity to kill.

The State Department noted that the group continues to threaten the Greek government and media, and that it follows each attack with written proclamations warning of more violence.

Greece has been wracked by unrest linked to its dismal economic performance and high unemployment. Authorities brought homicide charges Thursday against a man suspected of carrying a longbow and an ax at a violent demonstration in Athens designed to protests sharp cuts in public spending.

The State Department has named more than 80 individuals and groups to the terrorism list.



State Department's terrorism list:

CIA background on Greece: