WASHINGTON (Yonhap News) ― In a further clarification of its view on a key history issue between South Korea and Japan, the U.S. government said Tuesday that Japan’s trafficking of Korean women for sex services during the World War II is an unassailable “fact.”

“These were women who were trafficked for sexual purposes,” a State Department official told Yonhap News Agency.

The official stressed that how to characterize the incident is more important than the terminology to describe the victims.

“Rather than focusing on the label placed on these victims, we prefer to address the fact that this was a human rights violation of enormous proportions,” the official said on the customary condition of anonymity.

The official was responding to recent South Korean media reports that Secretary of State Hillary Clinton had instructed her department to use the words “enforced sex slaves,” not just “comfort women.”

Various records show that Japan’s government organized the enslavement and rape of hundreds of thousands of Korean and other Asian girls and women during its imperialist colonization.

Japanese authorities are under renewed pressure to address the issue as the U.S. House of Representatives marks the fifth anniversary this month of the adoption of a landmark resolution on comfort women.

The resolution calls on Japan to “formally acknowledge, apologize and accept historical responsibility in a clear and unequivocal manner” for its past “coercion of young women into sexual slavery.”

It was introduced by Rep. Mike Honda (D-CA), a Japanese-American lawmaker, and co-sponsored by 167 lawmakers of both parties.

A U.S.-based civic group, named Korean American Civic Empowerment (KACE), held a ceremony at the Capitol Tuesday to commemorate the resolution.

Honda and two former comfort women survivors were among the participants.

The event is a “great opportunity to share the stories about how the resolution contributed in improving human rights and women’s rights and what should be done for our continued efforts for the comfort women survivors,” said Kim Dong-chan, head of KACE.