The foreign ministers of South Korea and Japan will Monday to try to resolve the decades-long thorny issue of Korean women forced into Japanese military-run brothels during World War II, Seoul officials said.

The issue of former Korean sex slaves, euphemistically known as "comfort women," is the biggest source of friction in ties between Seoul and Tokyo, which suffered further setbacks after the late 2012 inauguration of hawkish Japanese Prime Minister Shinzo Abe.

Last month, the leaders of the countries resumed formal talks after a 3 ½-year hiatus and agreed to try to resolve the sex slave issue. There have since been positive developments, such as a Seoul court's acquittal of a Japanese reporter charged with defaming South Korea's president.

It wasn't clear if Monday's meeting between South Korean Foreign Minister Yun Byung-se and his Japanese counterpart Fumio Kishida would produce any breakthroughs. Japan has apologized many times before over the women, but many South Koreans see the statements and past efforts at private compensation as insufficient.

The women are the legacy of Japan's brutal colonial occupation of the Korean Peninsula from 1910-1945. Many South Koreans still harbor bitter resentment over that period, but South Korean officials have also faced calls to improve ties with Japan.

Despite their harsh history, South Korea and Japan are closely linked commercially and are key security allies of the United States in the region. Strained ties between Seoul and Tokyo is a headache for Washington, which wants to strengthen its alliance with the two countries to better cope with a rising China and North Korean military threats.

South Korea and Japan together host about 80,000 U.S. troops and are members of now-stalled regional talks aimed at ending North Korea's nuclear ambitions in return for aid.