Seoul, South Korea ? South Korean and U.S. intelligence authorities have detected suspicious vehicle movements in and out of North Korea’s major missile test site, a news report said today.

The intelligence authorities do not rule out the possibility that it is part of North Korea’s preparations for additional missile tests, Yonhap said.

The communist regime launched a barrage of missiles in July, heightening regional tensions and drawing international condemnation.

National Intelligence Service, South Korea’s spy agency, said it “was keeping a close watch on Gitdaeryeong area.”

North Korea on Saturday accused the United States of threatening war against the communist country with its missile defense test and vowed to boost its own self-defense to counter any U.S. attack.