TOKYO (Reuters) - Japanese Prime Minister Shinzo Abe said on Thursday that he agreed with Russian President Vladimir Putin that North Korea s latest nuclear test is a serious threat to regional peace and a challenge to global nuclear non-proliferation regime.    Abe made the comments after holding talks with Putin on the sidelines of an economic forum in Russia s eastern port city of Vladivostok.   We completely agreed that North Korea s nuclear test is a serious threat to the peace and stability of Korean peninsula as well as the region, and a grave challenge to the global non-proliferation regime,  Abe told reporters.   