Thursday's launches, on the other hand, did not violate the resolution, according to South Korea's Foreign Ministry. Kim Tae-woo, vice president of the Korea Institute for Defense Analyses, said it was believed North Korea launched cruise missiles Thursday.

Ballistic missiles are guided during their ascent out of the atmosphere but fall freely when they descend. Cruise missiles fly low and straight to their target.

The North has a record of timing missile tests for the U.S. national day, which fell on Saturday.

"The missiles were seen as part of military exercises, but North Korea also appeared to have sent a message to the U.S. through the missile launches," a senior official in South Korea's presidential office said, without elaborating.

The official told The Associated Press that North Korea could fire more missiles in coming days, but said there was little possibility it could fire an intercontinental ballistic missile, as it threatened in April.

He spoke on condition of anonymity because he was not authorized to speak to media.

Daniel Pinkston, a Seoul-based analyst for the International Crisis Group think tank, said both political and military reasons were behind the launches.