By Carol Gluck, professor, Columbia University

Three overlapping reasons help to explain why the issue of the "comfort women" has gained increased international prominence today.

First, during the 1990s, violence against women in wartime became part of international law for the first time. The violation of the human rights of women (women's rights), the "rape camps" in the Bosnian conflict, and the international attention in the U.N. and elsewhere to the "comfort women" resulted in rape and forced prostitution being defined as crimes against humanity in the 1998 Rome statute of the International Criminal Court.

The legal arguments leading to this historic development often mentioned the "comfort women" as examples of past victims of the kind of sexual violence now declared criminal in international law.

Second, the expansion of activities of NGOs, especially those devoted to women's issues, combined with increased international cooperation among them to give the "comfort women" a presence in global civil society. The movement began in South Korea in the late 1980s, followed by women activists in Japan and in other Asian nations from which the "comfort women" came. Asian-American and Asian-Canadian women added their voices to the outcry. In the United States in the 1990s, the issue became part of ethnic identity politics and was included in several Congressional Resolutions calling on the Japanese government for recognition, compensation and apology.

Third, the "comfort women" issue was taken up at government levels in new and vocal ways. In 2011, for example, the Constitutional Court of Korea ruled as unconstitutional the South Korean government's neglect in seeking a solution with the Japanese government on compensation for the former "comfort women." This marked the beginning of a new phase in which the South Korean government demanded formal negotiations with the Japanese government and also appealed to the international community through the U.N. in New York and Geneva.

In July, a United Nations Human Rights panel called on the Japanese government to investigate and take responsibility for the "comfort women" system and to compensate and apologize to former "comfort women." Similar demands were written into law by the U.S. Congress last January, and the "history problem" became part of American diplomatic language when dealing with Japan and Korea.

These three factors have in common that they are all international in reach and that they reveal changes in attitudes toward the politics of memory and women's rights over the nearly quarter century since the "comfort women" issue first claimed broad public attention.

When Japanese public figures deny the coercive character of the "comfort women" system or question the evidence relating to it, they are contesting what has become a widening global consensus about violence toward women in war and strengthening international criticism of the Japanese reluctance to confront the issue with acknowledgment, apology and compensation.

The growing number of "comfort women" monuments in the United States exemplifies this kind of reaction: more Japanese denials bring more statues, more Japanese objections to the statues bring more public criticism, more public criticism makes the issue loom ever larger. Neglecting, ignoring, or denying the "comfort women" issue is not likely to make it disappear.

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Born in 1941, Carol Gluck is the George Sansom Professor of History at Columbia University. A leading U.S. researcher of modern Japanese history, she has written many books, including "Rekishi de kangaeru" (Thinking with history).

(A Japanese version of this article appeared in August in the print edition of The Asahi Shimbun and Asahi Shimbun Digital. The English version is not identical to the Japanese version, which was edited due to space limitations.)