SEOUL (Reuters) -South Korean President Lee Jae Myung, who has been seeking to improve strained relations with Pyongyang, ordered on Monday his cabinet to prepare a partial step-by-step implementation of existing agreements with North Korea.

South Korea and the United States began their annual large-scale joint military exercise on Monday to better cope with threats by nuclear-armed North Korea, which has warned the drills would deepen regional tensions and vowed to respond to any provocation against its territory.

In a speech to mark the 80th anniversary of Korea's liberation from Japanese colonial rule, Lee said he would restore the so-called September 19 Comprehensive Military Agreement, a de-escalation measure that halted some military activities at the border between North Korea and South Korea.