Buhari , who is meeting Obama during a visit to the U . S . capital , made the call in an opinion article published Monday in the Washington Post. The fact that I now seek Obama’ s 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 is a testament to how badly Nigeria has been run , ” he wrote. “ This way of conducting our affairs cannot continue. ” Buhari , who took office on May 29 after defeating Goodluck Jonathan in the March elections , pledged during his campaign to clamp down on graft , including the oil industry that provides Africa’ s biggest economy with about two- thirds of government revenue and 90 percent of export earnings .