Raising tensions with South Korea yet again, North Korea on Wednesday cut its last military hotline with Seoul, a link that has been essential to running the last major symbol of inter-Korean cooperation: an industrial complex in the North that employs hundreds of workers from the South.

There was no immediate word about what cutting one of the few remaining official North-South links means for South Korean workers at the Kaesong industrial complex. When the link was last cut, in 2009, many South Koreans were temporarily stranded in the North.

The hotline shutdown is the latest of many provocative actions and threats from North Korea, which is angry about U.S.-South Korean military drills and recent U.N. sanctions punishing it for its February nuclear test. In a statement announcing the shutdown, the North repeated its claim that war might break out at any moment.

Outside North Korea, Pyongyang’s actions are seen in part as an effort to spur dormant diplomatic talks with a view toward gaining aid, as well to strengthen internal loyalty to young leader Kim Jong Un and build his military credentials.

South Korean officials said that about 750 South Koreans were in Kaesong on Wednesday and that the two Koreas had normal communications over the hotline earlier in the day, when South Korean workers traveled back and forth to the complex as scheduled. The hotline is used by the countries’ militaries to arrange border crossings by the workers.

Workers at Kaesong could be contacted directly by phone from South Korea on Wednesday.

A South Korean employee of Pyxis, a company that produces jewelry cases at Kaesong, said in a phone interview that he wasn’t scared.

“It’s all right,” he said. “I’ve worked and lived with tension here for eight years now. I’m used to it.”

Pyongyang’s action was announced in a message that North Korea’s chief delegate to inter-Korean military talks sent to his South Korean counterpart.

Seoul’s Unification Ministry called the move an “unhelpful measure for the safe operation of the Kaesong complex.”

North Korea recently cut a Red Cross hotline with South Korea and another with the U.S.-led U.N. command at the border.

The Unification Ministry said three telephone hotlines remain between the North and the South, and those are used only for exchanging information about air traffic.

— Associated Press