North Korea has issued repeated complaints in recent weeks about alleged American spy flights, including in skies off the coast where a missile test facility is located. On Thursday, the North admonished Washington again. "Military provocations by US warmongers against (North Korea) are reaching their extreme," the North's Korean Central News Agency said in a report. "The series of illegal infiltrations and spying by reconnaissance planes of US aggression forces is creating a danger of military clash in the skies" over the area. The US has sent ships off the Korean coast that would be capable of detecting and tracking a missile launch, a Pentagon official said Wednesday.