Yoon earlier said that Seoul is negotiating with Washington to jointly plan and conduct exercises with the participation of US nuclear forces to counter North Korea's nuclear threat.
"No," Biden said when asked if he was discussing joint nuclear exercises with South Korea.
Following Biden's remarks, the office of the South Korean president clarified what exactly the nuclear cooperation between the two countries implied.
"Joint nuclear exercise is a term used between nuclear powers. [Thus, when a reporter asked Biden] if joint nuclear exercises are being discussed, [he had to say] no," South Korean senior presidential secretary for press affairs Kim Eun-hye stated.
According to Kim, the two countries are in regular discussions on sharing related information in the field and on planning and implementing US nuclear operations.
The situation on the Korean Peninsula has become more tense as North Korean leader Kim Jong-un ordered the development of a new intercontinental ballistic missile system last week to conduct a quick nuclear retaliatory strike. He also said that the United States, under the pretext of strengthening cooperation with South Korea and Japan, was creating an "Asian version of NATO."
In response, Seoul said that measures announced by Pyongyang were "absurd" and would only worsen the situation.