Nigeria's President Muhammadu Buhari was sworn in for a second term on Wednesday, promising once again to tackle crippling security threats and end rampant corruption in Africa's largest democracy.

President Buhari opted not to make a speech or any other public comment following taking the oath of office during Wednesday's ceremony.

In addition to fighting corruption and security threats, Buhari will also have to figure out to revive Nigeria's sagging, oil-dependent economy.

A massive drop in global oil prices sent the country into a recession. Nigeria's economy has since recovered and GDP is on the rise. However, like in many parts of Africa chronic unemployment remains a problem. More than 90 million people in Nigeria live in poverty. That is the highest number of impoverished people in the world, according to the U.S.-based Brookings Institute.

Mr. Buhari won 56% of votes in February's presidential election after promising to end violence in the northeast, extend welfare programs and kickstart growth with a program of road and rail construction.

But the fighting with the Islamist militants of Boko Haram and other groups has shown no sign of abating.

A separate surge of bandit attacks and other violence in the northwest has forced 20,000 refugees to flee to neighboring Niger.