The U.S. State Department has added members of the radical islamic group Boko Haram to its list of international terrorists.
The action follows growing pressure on the Obama administration to take stronger action against the group that has terrorized Nigerian Christians for years.
State Department spokeswoman Victoria Nuland described Boko Haram leaders Abubakar Shekau, Abubakar Adam Kambar, and Khalid al-Barnawi as "kingpins" of the radical Islamist group.
The department called Shekau the group's "most visible' leader. It said the men have close ties with al Qaeda.
"Shekau has publicly stated the goal of overthrowing the government of Nigeria and an interest in instituting strict Shariah," Nuland told reporters Thursday.
Designating the men as global terrorists blocks any assets the men may have in the U.S. and bars Americans from doing business with them.
The radical Islamic group has been targeting churches in Nigeria for years. It has killed hundreds of Christians this year alone.
Last weekend, the group bombed three churches there. At least 138 people have been killed in attacks throughout this week alone.
A Boko Haram spokesman said the group has declared war on Nigeria's government, the security services, and the country's Christians.
In a video released online he said, "I enjoy killing anyone that God commands me to kill the way I enjoy killing chickens and rams."
Meanwhile, Republicans in Congress are considering mounting more pressure on President Obama to go beyond labeling the men as terrorists and designate Boko Haram as a foreign terrorist organization.