South Korean cars returning from inter-Korean Kaesong Industrial Complex in North Korea, arrive at a gate of the inter-Korean transit office in the border city of Paju on April 30, 2013.

SEOUL, South Korea — North Korea warned Tuesday that it would never forgive South Korea if it moved to shut down a joint industrial complex in the border city of Kaesong.

The joint project, combining South Korean capital and expertise with North Korean labor and land, had been the last remaining symbol of economic cooperation between the two Koreas.

However, the future of the complex was thrown into doubt after both sides withdrew all of their workers from the zone, Yonhap news agency reported.

North Korea pulled out its 53,000 laborers from Kaesong on April 9, in protest over joint military exercises by the US and South Korea. It also prevented South Korean managers and supply trucks from entering the complex.

And all but seven South Korean workers left the complex on Tuesday, a source at South Korea's Unification Ministry said.

However, the New York Times reported that those remaining South Koreans were only there for "a few days to sort out a dispute over unpaid wages."

It added:

When that is settled, South Korea is expected to turn off the electricity it supplies to the complex, which until now has been one of the most brightly lighted parts of North Korea, a country shrouded in darkness at night because of a severe lack of fuel.

More from GlobalPost: Full coverage of the tensions in the Koreas

GlobalPost senior correspondent in Korea, Geoffrey Cain, said that "many analysts in Seoul agree that the issue at Kaesong has evolved into a tit-for-tat.

North Korea first withdrew its workers, claiming it was angry that South Koreans speculated the North needed the revenues from the zone. North Korean leaders waited to see how far the South would go in response, and since then, both sides have stepped up their game."

Neither side wants to be blamed for closing the industrial complex first, Cain continued.

"But pretty much every expert in Seoul didn't predict that the situation would escalate so quickly. Many were surprised that the North not only suspended operations — but that both sides withdrew workers indefinitely."

After the North ignored a deadline for talks aimed at normalizing operations there, South Korea announced on Friday that it would withdraw all personnel.

The complex started operations in 2004 and until this month had 800 South Korean managers and delivery staff.

The facility provided a much-needed economic benefit to the North.

A separate Yonhap article said that since 2004, South Korea had invested about $1 billion in the complex.

The report said that using North Korean labor, South Korean investors had so far produced about $1 billion worth of garments, wristwatches and other labor-intensive goods there.

In return, the North earned $245 million in wages.

Were the Kaesong facility to shut for good, the administration of new South Korean President Park Geun-hye would face trouble pushing forward its trust-building policy with the North.

A Seoul government official told Yonhap:

"Counting the number of North Korean workers and their dependents, Kaesong supported roughly 200,000 people in the communist country."

Geoffrey Cain contributed to this report from Seoul.

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