As state intervention and take-over of privately owned businesses continued, trade restrictions on Cuba increased. The U.S. stopped buying Cuban sugar and refused to supply its former trading partner with much needed oil, with a devastating effect on the island's economy, leading to Cuba turning to their newfound trading partner, the Soviet Union, for petroleum. In March 1960, tensions increased when the French freighter "La Coubre" exploded in Havana Harbor, killing over 75 people. Fidel Castro blamed the United States and compared the incident to the sinking of the "Maine", though admitting he could provide no evidence for his accusation. That same month, President Eisenhower quietly authorized the Central Intelligence Agency (CIA) to organize, train, and equip Cuban refugees as a guerrilla force to overthrow Castro.