South Korea plans to plant about 7,000 trees around a jointly run factory park in North Korea, an official said Thursday, despite heightened military tensions on the Korean Peninsula. Some 70 South Korean officials plan to plant the retusa fringe trees in and around the factory park in Kaesong, just north of the heavily fortified inter-Korean border, on Thursday and Friday to mark Arbor Day, which falls on Saturday, the official of the unification ministry said. The move comes despite tensions over the exchange of fire by the rival Koreas across their disputed western maritime border, as well as Pyongyang's threat of a nuclear test. The factory park, the last remaining symbol of inter-Korean cooperation, is home to 120 small South Korean factories producing garments, shoes, watches and other labor-intensive goods. More than 44,000 North Koreans work in the complex. Global Forest Watch, which is run by the Washington-based World Resources Institute, said last month that North Korea has destroyed forests about 18 times the size of Manhattan for more than 10 years.