TOKYO (Reuters) - Japanese Prime Minister Shinzo Abe said on Tuesday that it is important to change North Korea s policy by imposing a higher level of pressure on the country than ever before. Abe told reporters that Japan wants to exercise leadership to bring about change in Pyongyang s policies through close cooperation with the international community. The United Nations Security Council unanimously stepped up sanctions against North Korea on Monday over the country s sixth and most powerful nuclear test on Sept. 3, imposing a ban on the country s textile exports and capping imports of crude oil. 