A joint South-North Korean industrial zone was operating normally Thursday, officials said, despite Pyongyang severing a military hotline used to monitor movement in and out of the zone.
Around 160 South Koreans passed through the border control Thursday morning to the South-funded Kaesong industrial complex which lies 10 kilometers inside North Korea.
"Movement to Kaesong is going ahead normally," said an official at the South's Unification Ministry.
There had been concerns that operations at the complex would be affected by the North's announcement Wednesday that it was snapping its last military hotline with the South.
The line was used daily to provide the North with the names of those seeking entry to Kaesong.
Kaesong was established in 2004 as a symbol of cross-border cooperation. North Korea has always been wary of allowing crises in inter-Korean relations to affect the zone.
The Unification Ministry official said a civilian telephone line had been used to relay the names of visitors to the border guards via the Kaesong management committee.
Nevertheless, the Unification Ministry formally requested the North reconnect the military hotline, saying its suspension could impact "stable operation" of Kaesong, where more than 50,000 North Koreans work at small, labor-intensive South Korean plants.
The North said it was cutting the military hotline to protest recent South Korean-US military exercises, which are held every year and are regularly condemned by Pyongyang as rehearsals for invasion.
Their staging this year fuelled tensions created by the North's recent long-range rocket launch and nuclear test.
Two nuclear-capable B-2 stealth bombers flew "deterrence" missions over South Korea Thursday, intending to send a potent message to Pyongyang about the US commitment to defending South Korea against any aggression.
The two B-2s, from Whiteman Air Force Base in Missouri, flew the 20,800-kilometre round-trip in a "single continuous mission," dropping dummy ordnance on a target range in the South, the US military said in a statement.
"This ... demonstrates the United States' ability to conduct long-range, precision strikes quickly and at will," the statement said, stressing that the US is "steadfast" in its alliance commitment to the defense of South Korea.
The US and South Korean militaries signed a new pact last week, providing for a joint military response to even low-level provocation by North Korea.