Kathleen Stephens, an iconic figure in recent South Korea-U.S. ties, emphasized Wednesday that Washington's alliances with Seoul and Tokyo are not a zero-sum game.

Japan's gain does not have to be Korea's loss, or vice versa, she said.

She dismissed a view that the U.S. is sandwiched between Japan, apparently seeking to expand the role of its self-defense forces, and South Korea, which remains wary of Japan's possible return to military imperialism.

"I think what has held true for a long time is still our guiding principles that are far from feeling sandwiched," Stephens, a senior U.S. diplomat, said in an interview at the State Department here.

"The United States greatly values its close alliance with the Republic of Korea, of course, and also our close alliance with Japan," she added.

It was her first formal interview with the Korean press since she wrapped up a three-year stint as ambassador to Seoul in October.

Currently, she is taking a break from hands-on diplomacy, working as a senior research associate at Georgetown University.

Her remarks came in response to a question over the possibility that the Seoul-Washington alliance will be hurt by the often-prickly relations between Tokyo and Seoul.

Japan seems intent on building up its military power, putting South Korea and other Asian neighbors on alert.

Critics accuse the U.S. of maintaining a lukewarm stance on the matter.

Stephens said the U.S. understands such "historical challenges" in relations between South Korea and Japan.

She said Japan needs to make more efforts to address the issue of Korean women forced to serve as sex slaves for Japanese troops during World War II.

She said it's her own view and also that of the U.S. government that "it's clear that Korean women who were forced into sexual slavery during that period suffered grievous harm and horrendous violation of their human rights, and this is a very painful chapter that is not forgotten."

"I think it's important for Japan to continue to find ways to address this in a way" to foster a constructive relationship with South Korea, she added.

On North Korea, Stephens said it is a "painful thing" to see North Koreans suffer without new opportunities as citizens in the 21st century.

"We want to try to keep sending the message that we are ready to see a different kind of future for North Korea," she said.

Regarding her future career, Stephens said she will first focus on her writing and teaching at the university this year.

Stephens was guarded about next steps, saying only she is willing to do anything and go anywhere to contribute to U.S.-South Korea relations.

"South Korea remains still alive in my heart, although I returned from South Korea last October," she said in Korean at the end of the interview.

Stephens speaks fluent Korean but she uses English in formal events.

She said she plans to write a book on Korea, but did not elaborate.

Stephens was arguably the most beloved U.S. ambassador to South Korea, leading many Koreans to abandon their traditional view of top American diplomats there as "high-handed."

Her efforts to reach out to ordinary Koreans were seen as a good model of public diplomacy. She crisscrossed the country to meet people and won their hearts with a humble attitude.

Her ties with South Korea date back three decades to when she worked as a Peace Corps volunteer there. She has a self-assigned Korean name, Shim Eun-kyoung, from her Peace Corps days. (Yonhap News)