Conceding that Islamic extremists control some of his country’s villages and towns, Nigeria’s president declared a state of emergency Tuesday across the troubled northeast, promising to send more troops to fight what he said is now an open rebellion.

President Goodluck Jonathan, speaking live on state radio and television networks, also warned that any building suspected of housing Islamic extremists would be taken over in what he described as the “war” now facing Africa’s most populous nation. However, it remains unclear what the emergency powers will do to halt the violence; a similar, earlier effort failed to do so.

“It would appear that there is a systematic effort by insurgents and terrorists to destabilize the Nigerian state,” Jonathan said.

Jonathan said the order will be in force in Adamawa, Borno and Yobe states, which will receive more troops. Under Nigerian law, the president has the power to install a caretaker government in emergencies, but Jonathan said he would not remove state politicians from their posts.

The president’s speech offered a stark vision of the ongoing violence, often played down by security forces and government officials for political reasons. Jonathan described the attacks as a “rebellion.”

“Already, some northern parts of Borno state have been taken over by groups whose allegiance are to different flags than Nigeria’s,” Jonathan said. “These actions amount to a declaration of war and a deliberate attempt to undermine the authority of the Nigerian state.”

Since 2010, more than 1,600 people have been killed in attacks by Islamic insurgents, according to an Associated Press count. Meanwhile, violence pitting different ethnic groups against each other continues unabated, with clashes in which dozens are killed at a time. In addition, dozens of police officers and agents of the country’s domestic spy agency were recently slaughtered by a militia.

One of the main Islamic extremist groups fighting Nigeria’s weak central government is Boko Haram, whose name means “Western education is sacrilege” in the Hausa language of Nigeria’s north. The group has said it wants its imprisoned members freed and strict sharia law adopted across the multiethnic nation of more than 160 million people. It has sparked several splinter groups, and analysts say its members have contact with two other groups in Africa linked to al-Qaeda.

— Associated Press

Nigerian President Goodluck Jonathan speaks May 14 during a nationwide live broadcast on state television. (PIUS UTOMI EKPEI/AFP/GETTY IMAGES)