Munsan, South Korea ? Trains crossed into the heavily fortified Demilitarized Zone today for the first rail journey through the border dividing the two Koreas in more than half a century, the latest symbol of historic reconciliation between the longtime foes.

The one-time test run of trains through the 2 1/2-mile no man’s land along two restored tracks on the west and east sides of the peninsula comes after repeated delays since the rail lines were linked in 2003 – and despite unresolved tensions over the North’s nuclear weapons.

“It is not simply a test run. It means reconnecting the severed bloodline of our people. It means that the heart of the Korean peninsula is beating again,” Unification Minister Lee Jae-joung said at a ceremony at Munsan station, 7 miles south of the Demilitarized Zone, before boarding the train.

The two Koreas “should not be derailed from the track or hesitate” in their moves toward unification, North Korean Senior Cabinet Councilor Kwon Ho Ung said.

However, Kwon also repeated the North’s claims that outside powers – usually a reference to the United States – were the main obstacle to reconciliation between the Koreas.

“Even at this point, challenges are continuing from divisive forces at home and abroad who don’t like reconciliation and unification of our people,” Kwon said.

The tests include two five-car trains with 150 people aboard – one departing from the North and another from the South. Both trains were to return later today after spending a few hours on the opposite side.