U.S. Secretary of State Rex Tillerson has told Foreign Minister Taro Kono that Washington is considering a multilateral defense ministers' meeting aimed at reining in North Korea's nuclear and missile development programs, sources have said.

In their meeting in New York on Dec. 15, Tillerson told Kono the meeting should be held if North Korea continues its provocations, even after a similar meeting of foreign ministers is held in Vancouver in mid-January to step up international pressure on Pyongyang, the sources said Monday.

Tillerson also stressed to Kono the necessity of dialogue with North Korea, expressing concern that the actions of North Korean leader Kim Jong Un are becoming increasingly difficult to predict, the sources said.