The United States and other nations are prepared to help move an expanded African peacekeeping force into position in Sudan's Darfur region to halt the bloodshed, national security adviser Condoleezza Rice said on Sunday. President George W. Bush has declared that the violence in Darfur amounts to genocide and has urged the world to expand an African peacekeeping force. "The key is ... to get an augmentation of the African Union force that is already on the ground," Rice told CNN's "Late Edition." "Rwandans are ready to go. Nigerians are ready to go. We are prepared, with others, to help get them there," she added. "We're actively involved in trying to get Khartoum to stop this terrible tragedy." Sudan has rejected the genocide declaration as American "posturing" and several U.N. Security Council members have raised objections to a draft resolution on Darfur circulated by Washington. On another program, U.S. Secretary of State Colin Powell said efforts to bring the security situation under control were not working. --More 2300 Local Time 2000 GMT