Undersecretary-General for Political Affairs Jeffrey Feltman is scheduled to meet Foreign Minister Ri Yong Ho, Vice Minister Pak Myong Guk, diplomats and United Nations staff during his stay.
The United States and South Korea conducted large-scale military drills this week, which the North said have made the outbreak of war "an established fact".
Feltman, the highest-ranking American in the U.N. Secretariat, is the first person in that post to visit North Korea since February 2010.
North Korea's official news agency on Wednesday quoted an unnamed Foreign Ministry spokesman strongly criticizing senior USA administration officials' "bellicose remarks" and the ongoing military exercises.
KCNA said Pyongyang considers the joint drills part of a US "scheme to make a surprisingly preemptive nuclear strike" on North Korea.
North Korean leader Kim Jong Un and U.S. President Donald Trump, meanwhile, have traded insults and engaged in escalating rhetoric in recent months.
Feltman arrived in North Korea on Tuesday and it is the first trip by a United Nations official to the isolated country in over seven years.
KCNA said North Korean officials and Feltman agreed that his visit helped deepen understanding and that they agreed to communicate regularly.
North Korea is also concerned about the effects global sanctions have had on the delivery of humanitarian aid.
He also visited a children's food factory and hospitals in Pyongyang on his trip.
Last month's missile test prompted a US warning that North Korea's leadership would be "utterly destroyed" if war were to break out.
"From North Korea's perspective, a country that has declared the completion of its nuclear weapons power, the dialogue was a great opportunity for their position to be presented to the global community", said Kim Yong-hyun, a professor of North Korean studies at Dongguk University in Seoul.