SEOUL, Jan 2 (AFP) - South Korea and the United States are discussing possible joint planning and exercises using U.S. nuclear assets in the face of North Korea's growing nuclear and missile threats, South Korean President Yoon Suk-yeol said in a newspaper interview.

The Chosun Ilbo newspaper quoted Yoon as saying the joint planning and exercises would be aimed at a more effective implementation of the U.S. "extended deterrence."

The term means the ability of the U.S. military, particularly its nuclear forces, to deter attacks on U.S. allies.

"The nuclear weapons belong to the United States, but planning, information sharing, exercises and training should be jointed conducted by South Korea and the United States," Yoon said, adding Washington is also "quite positive" about the idea.

Yoon's remarks come a day after North Korean state media reported that its leader Kim Jong Un called for developing new intercontinental ballistic missiles and a larger nuclear arsenal to counter U.S.-led threats amid flaring tension between the rival Koreas.

On Sunday, North Korea fired a short-range ballistic missile off its east coast, in a rare late-night, New Year's Day weapons test, following three ballistic missiles launched on Saturday, capping a year marked by a record number of missile tests.

Amid talk of South Korea's own nuclear armaments, Yoon said maintaining the Treaty on the Non-Proliferation of Nuclear Weapons remained important.