UNITED NATIONS (AP) — The U.N. Security Council officially declared Boko Haram a terrorist group linked to al-Qaida on Thursday and imposed sanctions against the Islamist extremists who have carried out a wave of deadly attacks and the recent abduction of nearly 300 schoolgirls in Nigeria.

U.S. Ambassador Samantha Power welcomed the council’s action, calling it “an important step in support of the government of Nigeria’s efforts to defeat Boko Haram and hold its murderous leadership accountable for atrocities.”