Nigeria's newly-elected president, Muhammadu Buhari, has vowed to spare no effort to defeat Islamist militants Boko Haram.
"In tackling the insurgency, we have a tough and urgent job to do," he said in a televised speech.
"Boko Haram will soon know the strength of our collective will. We should spare no effort until we defeat terrorism."
The 72-year-old former military ruler also elect also vowed to tackle corruption, which he described as an "even greater evil".
General Buhari of the All Progressives Congress (APC) became the first opposition candidate to win a presidential election in Nigeria, beating President Goodluck Jonathan by 2.5 million votes.
Much of General Buhari's support was in the north, in particular the north-east, which has suffered from Boko Haram's six-year insurgency. The militants have killed thousands of people in their drive to establish an Islamic state.
Many people accused Mr Jonathan of not taking Boko Haram seriously and thought General Buhari would be better positioned to defeat the militants.
The general, who first came to power three decades ago via a military coup and campaigned as a born-again democrat, also angrily denounced corruption.
"It creates unjustly enriched people ... and undermines democracy," he said. "Corruption will not be tolerated by this government."
Pledging to uphold the rule of law, the former military ruler said: "Your constitutional rights remain in safe hands - you will be able to voice your opinion without fear of victimisation."
Earlier, US President Barack Obama said the polls had shown the world the strength of Nigeria's commitment to democracy.
UN Secretary General Ban Ki-moon commended Mr Jonathan for statesmanship in upholding the democratic process.
- BBC / Reuters