Speaking to reporters, Wi Sung-lac, South Korea's envoy to the six-nation talks on the North's denuclearization, said Bosworth's decision to stop in Seoul before proceeding to Pyongyang showed the allies are drawing up a joint strategy, the Yonhap News Agency reported.
Bosworth added: "That was not an accident. We intended that," Yonhap reported.
The report said there had been concerns South Korea may be bypassed as the United States seeks to bring the Communist country back to the talks.
The six-nation talks remain stalled after Pyongyang pulled out following U.N. condemnation of its nuclear test and its tightening of sanctions. The talks also involve China, Russia, and Japan.
Bosworth was scheduled to leave for Pyongyang Tuesday. The talks with the North Koreans will be the first such direct contact for the administration of U.S. President Barack Obama, the report said.
Officially, the United States has said Bosworth's trip is only designed to bring the North back to the six-party format.
Earlier in London, Bosworth was quoted as saying: "I don't expect much from the first visit to the North."
North Korea was expected to seek the signing of a peace treaty to officially end the Korean War in exchange for its return to denuclearization talks, China's Xinhua news agency reported.
The 1950-1953 Korean War ended only in armistice, leaving the two Koreas technically in a state of war.