The Obama administration on Thursday named three leaders of the Nigerian militant group Boko Haram and a Basque separatist commander to the U.S. terrorism list.

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 that claimed responsibility for last year's deadly attack against a U.N. building in Nigeria's capital of Abuja.

The department called Shekau the group's "most visible" leader. It said Kambar and al-Barnawi have forged close ties with al-Qaida.

"Shekau has publicly stated the goal of overthrowing the government of Nigeria and an interest in instituting strict Shariah," or Islamic law, in the country, Nuland told reporters Thursday.

Designating these men as global terrorists blocks any assets the men may have in the U.S. and bars Americans from doing business with them. Nuland did not say if the U.S. had located any funds in the U.S.