North Korea: U.S. Conducting Spy Flights

North Korea said Sunday that a U.S. spy plane conducted aerial espionage missions against the communist nation three times last week and accused Washington of preparing to attack.

An overseas-based RC-135 plane flew above waters claimed by the North on Tuesday, Thursday and Saturday to spy on strategic targets, the North's official Korean Central News Agency quoted the country's air force command as saying in a report.

It called the flights "a wanton infringement" of North Korea's sovereignty and a violation of international law.

"The reality goes to clearly show how frantically the U.S. imperialist warmongers are working to ignite a war of aggression, openly crying out for a pre-emptive attack" on North Korea, the report said.

The North routinely accuses the U.S. of conducting spy flights. The U.S. military doesn't comment, although it acknowledges monitoring North Korean military activity.