"Regarding the naming of the East Sea, our consistent position is clear," Kim In-chul, spokesman of Seoul's foreign ministry, told a regular press briefing. "At present, our position is that the East Sea must be jointly used."

Seoul has been calling for cartographers around the world to juxtapose both names on maps. Experts here say that the East Sea is the oldest name for the waters while the Sea of Japan became known following Japan's colonization of the peninsula from 1910-45.

Trump mentioned the Sea of Japan in his Memorial Day remarks for US service members aboard the amphibious assault ship, USS Wasp, at a US naval base in Yokosuka, south of the Japanese capital.

"You face down terrorism, and render aid in the wake of devastating natural disasters," Trump said.

"You proudly patrol the Yellow Sea, the Sea of Japan, the East China Sea and the South China Sea ... You defend your homeland and our allies against missile attack with our most advanced radar and weapons systems in the world," he added.

Trump wrapped up his four-day state visit to Japan on Tuesday. During his stay there, he highlighted the strong alliance with Japan. He also met new Japanese Emperor Naruhito, becoming the first foreign head of state to meet him since his enthronement earlier this month. (Yonhap)