North Korea has test-fired two missiles off it eastern coast, South Korea said, in another provocative move after UN sanctions were imposed on the communist regime for its undergound nuclear test in May.

The missiles were fired between 8 am (2300 GMT) and 8:30 am (2330 GMT), South Korea's Joint Chiefs of Staff said in a statement. It did not say the range of the missiles.

"Our military is fully ready to counter any North Korean threats and provocations based on strong South Korea-US combined defense posture," the statement said.

A Yonhap news agency report said North Korea fired two short-range missiles that appeared to be Scud missiles. The agency quoted a South Korean government official it did not identify. Yonhap originally reported the missiles were mid-range.

North Korea fired four short-range missiles off the east coast on Thursday.

Speculation had been high that the communist country might launch more missiles in coming days. North Korea had warned shipping to stay away from its east coast effective through July 10.

South Korea's military said Friday it was closely monitoring North Korean military sites, believing more missile launches were likely.

Saturday's launches came on July 4, or U.S. Independence Day. The North has a record of timing missile tests for the U.S. national day.

In 2006, Pyongyang fired off a barrage of missiles, including a long-range Taepodong-2 that broke apart and fell into the ocean less than a minute after liftoff. Those launches while Americans were celebrating the Fourth of July holiday also came amid nuclear tensions with the U.S.

The bigger question is whether the North will attempt a long-range missile launch toward the United States, a move that would directly flout a U.N. sanctions resolution punishing Pyongyang for its May 25 nuclear test.

Firing a ballistic missile on July 4 would be a snub to Washington, which has been trying to muster international support for a tough enforcement of the U.N. resolution that bans Pyongyang from any further nuclear or ballistic missile tests.

Despite early speculation fueled by Japanese media and the North Korean warning to shipping, spy satellites have apparently not detected any of the preparations that would normally presage a launch.

Meanwhile, the chief of US Naval operations, Adm. Gary Roughead, said the American military was ready for any North Korean missile tests.

"Our ships and forces here are prepared for the tracking of the missiles and observing the activities that are going on," Roughead said after meeting Japanese military officials in Tokyo on Saturday.