SEOUL, South Korea — North Korea fired a barrage of short-range missiles off its east coast Thursday, a possible prelude to the launch of a long-range missile toward Hawaii over the July Fourth holiday.

Firing a ballistic missile on Independence Day would be a challenge to Washington, which has been rallying international support for enforcement of U.N. sanctions imposed against Pyongyang following a May 25 nuclear test. North Korea is banned from testing ballistic missiles under U.N. resolutions.

Japan's Chief Cabinet Secretary Takeo Kawamura said Thursday that a long-range missile launch this weekend was possible. "We cannot rule out the possibility," he said, citing Pyongyang's past behavior.

In 2006, North Korea launched its most advanced Taepodong 2 missile while the U.S. celebrated Independence Day, though the rocket fizzled shortly after takeoff and fell into the ocean.

Pentagon spokesman Bryan Whitman said the United States remains concerned about North Korea's missile and nuclear programs but called Thursday's launches "not unexpected."

Several U.S. Defense Department officials said there is nothing to indicate that North Korea is ready to launch a long-range ballistic missile and there appears to be no immediate threat to the United States.

The April 5 launch of a Taepodong-2 required 12 days of preparation on the launch pad, which was fully observable to U.S. satellites. Short and medium-range missiles, however, can be launched with little notice.

Missile defenses around Hawaii were beefed up following a mid-June report in a Japanese newspaper that the North might fire a long-range missile toward the islands in early July.

The head of the U.S. Northern Command, Gen. Victor E. "Gene" Renuart, said in an interview with the Washington Times this week that U.S. missile defenses are prepared to knock down any incoming North Korean missile. "I think we ought to assume there might be one on the Fourth of July," he said, according to the paper.

North Korea raised concern in late April when it explicitly threatened to test-fire an intercontinental ballistic missile and warned of a nuclear test. The regime followed through with the atomic blast in May, leaving the ICBM test as its next likely step.

"I totally expect that we will see another long-range missile launch ... because they said they will do it," Ralph Cossa, president of the Pacific Forum CSIS think tank, told The Associated Press from Beijing where he was attending a nonproliferation conference.