A plan being floated among Japan, the United States and South Korea is aimed at the complete denuclearization of North Korea by the summer of 2020, diplomatic sources said Tuesday, in a rejection of Pyongyang's "phased, synchronized" approach in exchange for benefits.The three countries are seeking an early end to Pyongyang's development of nuclear weapons and missiles after past attempts allowed North Korea incremental incentives to halt its nuclear program and led Pyongyang to buy time and further develop nuclear weapons, the sources close to Japan-U.S. relations said.The time frame for N…READ FULL ARTICLE