South Korea Warns North of "Grave Measure" in Factory Dispute SEOUL, South Korea - South Korea gave North Korea until Friday to respond to its proposal for dialogue or face a "grave measure" by the South on the future of a jointly operated industrial complex that has been the only remaining symbol of economic cooperation between the two Koreas. A statement from the South's Unification Ministry stopped short of saying whether it was contemplating withdrawing 176 South Korean managers still remaining in the factory park in North Korea or even terminating the joint economic project, which had survived years of political tensions on the divided Korean Peninsula. The future of the Kaesong Industrial Complex, located in the North Korean border town of the same name, has been in doubt ever since North Korea pulled out all its 53,000 workers on April 9 in anger over joint South Korean-U.S. military drills. It also blocked South Korean managers or supplies from entering the economic zone. The number of South Korean managers dwindled from the usual 900 to 176 as of Wednesday as supplies were running out. On Thursday, the South Korean government said that those who still stayed in Kaesong, hoping for the reopening of the complex, would not be able to remain much longer. It said when it tried on Wednesday to send a letter to the North through the border asking it to allow emergency food and medical supplies to be sent to South Koreans in Kaesong, the North did not even accept the document. On Thursday, it again proposed an official dialogue with the North and demanded the North respond by Friday. "Our government's position remains firm and unchanged - that the Kaesong factory park should be safely maintained and developed," said Kim Hyung-suk, a Unification Ministry spokesman, in a nationally televised statement. But we make it clear that if they again reject our proposal for government-to-government talk, we will have no option but to take a grave measure. There was no immediate response from the North. But it had earlier said that South Koreans in Kaesong were free to leave. It also demanded that the South first apologize for taunting its leadership. North Korea has said its decision to suspend operations at Kaesong was also due to insults from South Korean media analysts who have suggested that North Korea's leader, Kim Jong-un, would not dare shutter the Kaesong complex because he did not want to lose an important source of badly needed hard currency. The factory complex started operation in late 2004. The 123 South Korean factories there produced $470 million worth of textiles and other labor-intensive products last year and provided the North with $90 million a year in wages for its workers. The complex, where South Korea's manufacturing know-how was paired with cheap North Korean labor and the North's Communist authorities experienced the first taste of South Korean capitalism, has been held up as a test case for how reunification of the two Koreas might look. As relations deteriorated in recent years, however, the industrial park has also become a contentious issue in South Korea. Some conservative South Koreans argued that the complex extended a lifeline to the North Korean regime, which the South blamed for military provocations, including the 2010 sinking of a South Korean warship that killed 46 sailors. For several weeks, tensions have remained high on the peninsula as North Korea issued a torrent of threats to attack the United States and South Korea out of anger over U.N. sanctions imposed for its February nuclear test. The North Korean blockade pushed many of the South Korean companies that owned factories in Kaesong to the brink of bankruptcy. On Wednesday, the South Korean government offered these companies financial aid, including $8 million in special loans and $14.3 million in bank loans whose repayments can be postponed with government help. The factory park was a child of South Korea's now-defunct "Sunshine Policy" of encouraging economic cooperation with the North to ease military tensions on the divided Korean Peninsula.