Nigeria’s President Muhammadu Buhari is meeting his US counterpart, Barack Obama, to discuss the fight against Islamist militant group Boko Haram.
President Obama’s wife Michelle got involved in the online campaign, #BringBackOurGirls, after the group kidnapped some 200 girls last year.
The US sent surveillance flights over Nigeria to help locate them.
However, the US refuses to sell weapons to Nigeria because of concerns over its army’s human right record.
Mr Buhari wrote in an article published in The Washington Post just before meeting Mr Obama that “our allies can provide much-needed military training and intelligence as our soldiers take the war effort to Boko Haram”.
He also wrote that he was seeking US assistance in “locating and returning $150 billion in funds stolen in the past decade and held in foreign bank accounts on behalf of former, corrupt officials”.
At the outset of the meeting, President Obama praised the March elections won by Mr Buhari as “an affirmation of Nigeria’s commitment to democracy,” says AFP news agency.
President Buhari replied by saying Nigeria will “ever be grateful” for the US help in ensuring the elections were free fair and credible.
Mr Buhari, a former military ruler, was invited to Washington shortly after becoming the first opposition candidate to win a national election.
Nigeria is Africa’s most populous nation, biggest economy and biggest oil producer.
Analysis: Nasidi Adamu Yahaya, BBC Africa, Abuja
Nigeria is seeking US co-operation in combating Boko Haram militants.
The US had previously agreed to help Nigeria fight the insurgency, especially after more than 200 school girls were kidnapped by the militants group from their dormitory in Chibok early last year.
However, relations between the US and the administration of Nigeria’s former President, Goodluck Jonathan, soured, amid accusations of human rights violations by the Nigerian military.
President Buhari will also seize the opportunity to seek US assistance to recover billions of dollars from bank accounts in the United States, Switzerland and elsewhere.
The US and other G7 countries had promised to assist Nigeria discover the money – if the country could provide evidence that it had been stolen from the country.
Nigeria will also need US assistance in the fight against corruption, which is one of the issues the country’s president had promised to tackle during his campaign days.