At a press briefing in the Pentagon, Carter said he will be in South Korea next week to discuss "the ability of our collective defense to respond to those kinds of North Korean provocations."

He noted other activities by the North, including naval ones and actions along the Demilitarized Zone that divides the two Koreas.

"We're always concerned about North Korean behavior and provocations of all kinds," Carter said. "There's a constant potential for provocations."

Carter said his trip will include a visit to the DMZ but did not elaborate further.

A diplomatic source here said the secretary will be visiting South Korea for annual security talks, known as the Security Consultative Meeting, with his counterpart, Han Min-koo. (Yonhap)