The official Koran Central News Agency said Richardson and Schmidt landed Monday in Pyongyang. The Yonhap News Agency in South Korea, monitoring developments from Seoul, reported that Pyongyang provided few details about the itinerary.
Richardson, a former U.S. ambassador to the United Nations, has stated the trip is a private visit for humanitarian purposes.
U.S. State Department spokeswoman Victoria Nuland last week said the visit was frowned on by the White House but stressed it was a private matter.
"They are making their decision on that basis but they are well aware of our view of this," she said Friday.
Richardson said last week that he was making the trip to North Korea as a private citizen and Schmidt wasn't representing Google but were looking into winning the release of Kenneth Bae, U.S. citizen who is in a North Korean prison.