US Secretary of State John Kerry and his Republic of Korea counterpart Yun Byung-se confirmed on Monday a firm US-ROK alliance against any threats from the Democratic People's Republic of Korea.

Speaking to reporters at a news conference with Yun, Kerry said the US-ROK alliance "is absolutely stronger than ever", noting that there is "not an inch, not a centimeter," of difference between Washington and Seoul in their approach to Pyongyang's "provocations and its nuclear program".

"The biggest security concern" that the allies care about is the DPRK, Kerry said, adding that they "are working together with the same direction and the same goal."