Top U.S. and South Korea diplomats and defense officials are discussing their response to the growing threat from North Korea's nuclear and missile programs.

The meeting Wednesday comes weeks after the North's most powerful nuclear test explosion to date, and days after its failed test launch of a ballistic missile.

On the agenda is how to strengthen the so-called "extended deterrence" provided by U.S. nuclear forces in defending South Korea. Seoul is looking to allay calls from conservatives at home who want South Korea to develop its own nuclear arsenal.

The talks are between Secretary of State John Kerry and Defense Secretary Ash Carter, and their South Korean counterparts Foreign Minister Yun Byung-se (yoon pyuhng say) and Defense Minister Han Min-koo (hahn mihn-koo).