The United Nations aims to draw Pyongyang back to the negotiating table by sending a high-ranking official to the reclusive state, but whether the visit will produce any concessions from North Korea remains unclear.
On Monday, he met Chinese Deputy Foreign Minister Li Baodong, and from Beijing he will go directly to the North Korean capital.
He is now said to be in Beijing ahead of his departure to the North.
Jeffrey Feltman, undersecretary-general for political affairs, traveled to Pyongyang in response to an invitation by the North for a policy dialogue with the U.N. He is expected to meet with officials including Foreign Minister Ri Yong Ho.
Feltman, a former American diplomat who spent more than three decades at the U.S. Department of State, is the first senior United Nations official to visit the secretive North Korean state since former Emergency Relief Coordinator Valerie Amos did so in 2011, CNN reported.
An official of the U.S. state department said it was "aware" of the planned trip when asked if Washington backed the visit, reported Reuters.
North Korea invited Feltman for a "policy dialogue" when Ri was in NY in September for the U.N. General Assembly, according to a U.N. spokesman. His trip comes about a week after North Korea test-fired a new type of intercontinental ballistic missile that it says is capable of hitting the entire United States.
The visit by Feltman follows the dispatch last month by China of its highest-level envoy to North Korea in two years.
As well as featuring the latest generation of stealth fighters, this year's war games involve simulated precision attacks on the North's military installations, including its missile launch sites and artillery units, Yonhap news agency said, citing unnamed Seoul sources.
The U.N. earlier said Feltman will discuss "issues of mutual interest and concern" with North Korean government officials.