Despite the massive political scandal rocking South Korea, the US alliance with the Asian ally will "continue to function effectively" and deter threats from North Korea, the top US diplomat handling East Asian affairs said Thursday.

Assistant Secretary of State Daniel Russel said he hasn't seen any change in South Korea's national security line-up in the wake of the scandal surrounding allegations that a long-time confidante of President Park Geun-hye exercised huge influence over Park and state affairs.

"I'm not aware of any change in the national security team in Seoul and I don't see any change to any of the important priorities in the US-ROK alliance, including with respect to the timeline for the deployment of the THAAD system," Russel said during a Foreign Press Center briefing.

"We have every confidence that notwithstanding any political development in Seoul, the alliance will continue to function effectively as it has for more than six decades and we will continue to definitively deter and to further develop the capability to defend against the significant threat from the DPRK," he said.

Park has replaced top aides and Cabinet members, including the prime minister, finance minister and her chief of staff, nominating people long associated with opposition parties for those top jobs, in a desperate attempt to stanch the bleeding from the scandal.

But she left intact security-related ministers and aides.

Russel said that the THAAD missile system is purely defensive.

"There is a tendency to regard this as some sort of political gesture, whereas in fact it is a straight up defensive system that serves the function of protecting a finite area in the southern part of the Republic of Korea where the US military has important assets and our US forces and which is under threat by North Korea's missile program," Russel said.

"This is a necessary and common sense defensive measure. It is not political pawn and it is not intended as a signal to others, particularly not as a signal to China," he said. (Yonhap)