On 2 June 2010, Hatoyama announced his resignation as Prime Minister before a meeting of the Japanese Democratic Party. He cited breaking a campaign promise to close an American military base on the island of Okinawa as the main reason for the move. On 28 May 2010, soon after and because of increased tensions from the sinking of a South Korean navy ship allegedly by North Korea, Hatoyama had made a deal with U.S. President Barack Obama to retain the base for security reasons, but the deal was unpopular in Japan. He also mentioned money scandals involving a top party leader, Ichirō Ozawa, who resigned as well, in his decision to step down. Hatoyama had been pressed to leave by members of his party after doing poorly in polls in anticipation of an upper house election in July 2010.