WASHINGTON (AFP) - Secretary of State John Kerry said Friday it was too early to discuss cutting the number of US troops stationed in Asia and South Korea, amid increased tensions on the heavily guarded peninsula.

Speaking after talks with his South Korean counterpart Mr Yun Byung-se, Mr Kerry told reporters "it would be way too premature to have any thought of, or even discussion" about troop reductions, saying there first had to be real talks with North Korea over its suspect nuclear program.

"The only purpose of entering the talks is to come to an understanding regarding first the denuclearization and then following the denuclearization obviously whatever relationship might be appropriate," he said.

He also ruled out any idea of visiting isolated North Korea and meeting leader Kim Jong-un in the near term.

Washington and Pyongyang do not have diplomatic ties.

Mr Yun said South Korea was awaiting a "clear stance" on Pyongyang's nuclear policy and "a halt to the sophistication of its nuclear weapons."

"All of this has to be real. It has to lead to real solutions," Mr Yun said.