The U.S. Treasury Department blacklisted American al-Shabaab leader Omar Hammami, aka Abu Mansour al-Amriki, as well as a Kenyan fundraiser and recruiter for the organization. The sanctions bring to light al-Shabaab's efforts to recruit and fundraise from Western and East African communities.

"Hammami, a U.S. citizen, has been indicted in U.S. District Court in Southern Alabama on a three-count indictment for allegedly providing material support, including himself as personnel, to terrorists; conspiring to provide material support to a designated foreign terrorist organization, al-Shabaab; and providing material support to al-Shabaab," noted information accompanying the sanctions.

Hammami is recognized as one of the group's top military tacticians and trainers, a recruitment specialist who has focused on Western Muslims and the Somali diaspora, and a financial manager. He has organized suicide bombings, including an October 2008 attack in which a Somali-American from Minnesota killed more than 20 people. He has also featured in several of the group's recruitment videos, issuing statements in English and Arabic about the glories of fighting for an Islamic state.

Hassan Mahat Omar is a Kenyan recruiter and fundraiser for the organization, as well as an influential ideological leader of al-Shabaab. In this capacity, information accompanying his designation notes that he "exercises leadership and decision-making authority in al-Shabaab's internal political and operational decisions." A fatwa he issued against the Djibouti peace talks with Somalia's central government, is considered part of al-Shabaab's "religions justification to wage jihad against Somalia's Transitional Federal Government."

Omar is also "a key leader of a mosque in the Eastleigh section of Nairobi, Kenya, which he, along with known al-Shabaab leaders, uses to raise funds, recruit and disseminate propaganda on behalf of al-Shabaab." Kenyan and East African recruits have played an important role in filling gap's in the group's ranks, which have suffered al-Shabaab's brutal use of Sharia law and desertions.

The Treasury action freezes any U.S. assets belonging to the men and makes it illegal for people in the United States to engage in transactions with them.