As in the past when it has abruptly and without notice called off such reunions of families separated since the 1950-53 Korean War, Thursday's threat of a similar action came from North Korea's National Defense Commission, headed by the country's unpredictable leader Kim Jong Un.
The commission asked South Korea to scrap the annual military drills scheduled to begin at the end of this month and last through April. The North maintains the drills are designed for nuclear strikes against it despite the South's repeated assurances they are routine and defensive in nature.
"Dialogue and exercises of war of aggression cannot go hand in hand," South Korea's Yonhap News quoted the commission as saying in a statement aired by the regime's state-run radio.
The commission also suggested the reunions cannot be held if South Korea persisted with its slander but did not elaborate, Yonhap said. The report said the reference may have been to South Korean news reports that commented on Kim Jong Un's failure to remove his shoes when he visited a Pyongyang nursery.
The warnings came a day after North Korea agreed to the family reunions, which, if held, would have been the first such since October 2010. The agreement called for six-days of reunions starting Feb. 20 in Mount Kumgang, a scenic resort on North Korea's east coast.
Most family members living on either side of the Korean borders are now quite elderly, raising concerns about how much longer they have left to live.
Yonhap said South Korea's defense ministry immediately dismissed the North's demand, saying the drills would be held as planned. Currently, there about 28,500 U.S. troops based in South Korea.
State Department spokeswoman Jen Psaki, in her media briefing Wednesday, said the United States welcomed the agreement on the family reunions, calling them an example for improving inter-Korean relations. She also said the military drills are held annually.
"And they're designed to increase our readiness to defend South Korea once a year, protect the region and maintain stability on the Korean Peninsula," Psaki said.
The North Korean military commission also attacked the United States for flying a B-52 bomber over the peninsula Wednesday, Yonhap said. No details were available.
South Korean Unification Minister Ryoo Kihl-jae urged the North to honor its latest agreement on the family reunions.
Last year, the two sides agreed to hold similar family reunions but the North abruptly called them off at the last minute.
Tensions between the two Koreas have heightened as the North provoked ire with long-range missile firings and nuclear tests, the third of which was conducted a year ago in violation of U.N. sanctions. The six-nation talks on North Korea's denuclearization have been stalled for more than four years.
The South remains wary of any so-called charm offensive by the North, fearing such actions could lead to new provocations.