The top U.S. envoy on North Korea was in China Saturday on his weeklong trip to Asia to discuss cooperation in reining in a provocative Pyongyang, a diplomatic source here said.

Joseph Yoon began his trip to Beijing and Seoul on Friday and is set to arrive in Seoul on Monday, according to the source.

The trip by the special representative for North Korea policy of the State Department comes as the Donald Trump administration is reshaping its North Korea policy.

U.S. Secretary of State Rex Tillerson signaled a tough stance on the recalcitrant state during his ongoing trip to Asia this week. He said in Seoul Friday that the former Obama administration's so-called strategic patience approach to Pyongyang has ended.

While in Asia, Yoon was expected to hold separate talks with his Chinese and South Korean counterparts Wu Dawei and Kim Hong-kyun. 

Observers say Yoon may use his Asia trip to explore ways to further pressure Pyongyang into stopping its persistent provocations and renouncing its nuclear ambitions.

The recalcitrant regime has been raising tensions on the peninsula with a series of missile tests in recent months.

On March 6, the North fired off four ballistic missiles toward the East Sea in an apparent angry reaction to the ongoing military drills by Seoul and Washington, which it has denounced as a rehearsal for an invasion. 

The latest provocation came less than a month after its launch of a new intermediate-range ballistic missile that underscored how it is on course towards developing a nuclear-tipped ballistic missile that threatens not only South Korea but also U.S. bases in the Pacific rim. (Yonhap)