Hundreds of South Korean factory owners and supervisors crossed into North Korea Monday to restart production lines at a joint industrial park closed five months ago by threats of war.

Trucks and cars started rolling across the border shortly after 8:30am (2330 GMT Sunday)-- the result of weeks of often spiky negotiations aimed at easing tensions and reopening the Kaesong complex.

A South Korean man has escaped four decades after he was kidnapped by North Korea while fishing near the disputed Yellow Sea border, officials said Friday.

The 68-year-old, identified as Jeon Wook-Pyo, made it to Seoul recently after escaping from North Korea in early August, a government official said.

Russia on Thursday warned of a potential "man-made catastrophe" if North Korea restarts an aging plutonium reactor to boost its stockpile of nuclear weapons, after U.S. experts spotted steam rising from the Yongbyon facility.

The reactor, which was completed in 1986, is outdated and North Korea could suffer a major disaster if it is restarted, a Russian diplomatic source told the Interfax news agency.

North and South Korea agreed Wednesday to reopen their Kaesong joint industrial park on a trial basis from next Monday, five months after it was shut during soaring military tensions.

The setting of a date came after a marathon negotiating session that ran through the night, and marks a tangible step forward for recent efforts to improve cross-border relations.

North and South Korea held a second round of talks Tuesday on reopening their Kaesong joint industrial zone -- five months after it was shut down during soaring military tensions.

The newly formed Kaesong joint committee first met last week but was unable to reach any agreement on the timing for resuming operations at the complex.

North Korea held its second mass parade in little more than a month Monday, with leader Kim Jong-Un presiding over a display of goose-stepping paramilitary troops, marching bands and flower-waving civilians.

Leading the parade was the Worker-Peasant Red Guard -- a civilian militia with an estimated strength of more than three million active members.

South Korea and the United States have mapped out a joint operational plan which outlines concrete measures to deter and respond to North Korea's nuclear threats, a report said Sunday.

The plan encompasses political, diplomatic and military measures to specify how Washington will provide a nuclear umbrella for South Korea in the case of North Korean nuclear provocations, Yonhap news agency said.

Syrian President Bashar Assad has sent a message of congratulations to North Korea's leader Kim Jong-Un as the communist country marks its 65th anniversary, state media said Friday.

The Korean Central News Agency (KCNA) said Kim had received the message from Assad Thursday.

North Korea on Friday reconnected a military hotline to the South that was cut earlier this year at the height of cross-border tensions, Seoul's government said.

The line -- one of the two remaining inter-Korea military hotlines -- was disabled in late March weeks after the North's third nuclear test and the following month a joint industrial zone was shut down.

South Korea's defense ministry Thursday called for fresh attention to North Korean chemical weapons, suggesting such arms might have been traded between Pyongyang and Syria.

The warning comes amid international outrage over the Syrian regime's alleged use of chemical weapons against its own people.