Around 20,000 children in North Korea were shown on state-run media pledging allegiance to North Korean leader Kim Jong Un. Some South Korean news outlets described the ceremony, part of a six-day festival, as state propaganda.
North Korea, in response to media criticism, said it entered map coordinates of South Korean media offices into its military strike systems and demanded an apology from South Korean President Lee Myung-bak.
"We would like to ask the Lee group if it wants to leave all this to be struck by the (North) or opt for apologizing and putting the situation under control, though belatedly," Pyongyang said in a statement published by South Korea's Yonhap news agency.
South Korean Unification Ministry spokesman Kim Hyung-suk called on Pyongyang to end its policy of provocation.
Similar rhetoric from North Korea was expressed following April ceremonies marking the 100-year anniversary of Kim Il Sung's birth.
Authorities in Seoul said they didn't observe any noticeable movement from North Korea forces.
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