President Yoon Suk-yeol and US President Joe Biden are set to visit an Air Force operations center Sunday on the last stop of Biden's three-day trip to South Korea.

The two are scheduled to visit the Korean Air and Space Operations Center at Osan Air Base in Pyeongtaek, 70 kilometers south of Seoul, to be briefed on its work, and to encourage American and South Korean troops stationed there.

The visit is expected to underscore the allies' firm readiness against North Korea's nuclear and missile threats after Yoon and Biden agreed during Saturday's summit to expand the scope of combined military exercises.

Biden will be the first US president to visit the center, which is situated in an underground bunker and serves as a key command post for air and space operations, while Yoon will be the first South Korean president to do so in 13 years.

Before heading to the air base, Biden is scheduled to meet with Hyundai Motor Group Chair Euisun Chung.

On Saturday, the company announced plans to invest $5.54 billion in the construction of a dedicated electric vehicle and car battery manufacturing plant in Georgia, the US

Biden is set to head to Japan on Sunday afternoon. (Yonhap)