Earlier, South Korea's National Assembly impeached Park over a corruption scandal. Prime Minister Hwang Kyo-ahn took over as acting president while the Constitutional Court reviews the case for up to 180 days to determine whether to endorse or reject the impeachment.

"We look forward to working with Prime Minister Hwang in his new capacity as acting president of the ROK. We expect policy consistency and continuity across a range of fronts, including DPRK, other regional issues, and international economics and trade," the spokesperson said.

"The U.S.-ROK alliance will continue to be a linchpin of regional stability and security, and we will continue to meet all our alliance commitments, especially with respect to defending against the threat from North Korea," she said.

Since the corruption scandal broke and sparked massive protests, the White House has repeatedly stressed the firmness of relations with South Korea, saying the alliance transcends politics and has been strong through different administrations in both countries for decades.

U.S. President-elect Donald Trump is aware of the impeachment, his transition team said.

"The president-elect is aware of what's happening ... But that's something for the people of South Korea, not for us to weigh in on," transition team spokesman Jason Miller said at a regular conference call briefing.

Park was one of the first foreign leaders Trump spoke to since his election. 

During last month's phone conversation, Trump made a series of remarks reaffirming the alliance, such as "We are with you all the way and will not waver" and "We will be steadfast and strong with respect to working with you to protect against the instability in North Korea."

Top aides to Trump have emphasized the importance of the relations with South Korea. Mike Flynn, named to be Trump's first national security advisor, called the relations "a vital alliance" that should be further strengthened when he met with Seoul's deputy national security advisor last month. (Yonhap)