U.S. Assistant Secretary of State James Kelly and Mitoji Yabunaka, a senior official at the Foreign Ministry, held an "intensive discussion" Monday in Tokyo focusing on how North Korea may be given security assurances.
The talks form part of preparations ahead of a second round of six-way talks centering on Pyongyang's nuclear arms program.
Earlier in the day, Kelly held separate meetings with Chief Cabinet Secretary Yasuo Fukuda and Shinzo Abe, secretary general of the Liberal Democratic Party.