WASHINGTON, D.C.: With US-South Korean military drills back on the table and the cancelation of a top-level summit in Pyongyang, Washington is toughening its stance as it negotiates with North Korea.

Discussions have grown prickly after a historic summit in June between President Donald Trump and Pyongyang strongman Kim Jong Un, where the leaders embraced and pledged to work toward the 'complete denuclearization of the Korean Peninsula.'