The United States on Wednesday designated Nigeria's radical Islamist Boko Haram network and an offshoot known as Ansaru as terror groups, bowing to months of pressure to act. Both groups have spread terror in northeastern and central Nigeria and are blamed for thousands of deaths as they battle to set up an Islamic state. "These designations are an important and appropriate step, but only one tool in what must be a comprehensive approach by the Nigerian government to counter these groups ... to help root out violent extremism," the State Department said. "By cutting these terrorist organizations off from US financial institutions and enabling banks to freeze assets held in the United States, these designations demonstrate our strong support for Nigeria's fight against terrorism and its efforts to address security challenges in the north," White House homeland security advisor Lisa Monaco said.