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 Fourth of July 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 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.
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.
The North's April launch, which is estimated to have sent a rocket about 2,000 miles (3,200 kilometers), represented a "significant advance" in the country's long-range rocket technology, the Bulletin of Atomic Scientists said in a recent report.
South Korea believes the Taepodong 2 can travel at least 4,100 miles (6,700 kilometers), putting Alaska and Guam within striking distance. The North is also believed to be developing an advanced version of the Taepodong 2 that could reach not only Hawaii, but also the West Coast of the U.S. with a potential range of about 5,000 miles (8,000 kilometers).
Pyongyang had earlier marked a large area of water off its east coast as a no-sail zone through July 10, citing military drills. Thursday's launches of four short-range missiles were believed to be the North's first military action in the designated zone.
Yonhap news agency, citing an unnamed military official, reported that all four missiles flew about 60 miles (100 kilometers) and identified them as KN-01 missiles with a range of up to 100 miles (160 kilometers).
Japanese Prime Minister Taro Aso denounced the launches as "provocative." South Korea's foreign minister, Yu Myung-hwan, said the firings are "not a good sign because they are demonstrating their military power."
South Korean analysts were skeptical about the possibility of a long-range launch anytime soon.
Koh Yu-hwan, a professor at Seoul's Dongguk University, said he expects the North will take more time to assess international reaction to its recent pledge to expand its nuclear program.
Tensions over North Korea's actions come as its leader Kim Jong Il has reportedly been laying the groundwork to hand power over to one of his sons, and as two American journalists were imprisoned for illegal border crossing and hostile acts.
Analysts predict the North will continue its provocative acts in an attempt to command world attention that can lead to economic benefits.
"I think what North Korea will continue to do is ratchet up the tension," said Brad Glosserman, another analyst at the CSIS think tank. "It needs that attention to get the concessions from other countries ... as well as to demonstrate its strength to domestic constituencies."
President Barack Obama has vowed the U.S. won't make the same mistake of rewarding North Korea's bad behavior, and his administration has been pressing China -- a key North Korean ally -- to enforce the new U.N. sanctions against Pyongyang.
In an interview with The Associated Press Thursday, Obama said he was trying to "keep a door open" for North Korea to return to international nuclear disarmament talks, but the country must abandon its nuclear weapons programs before it can join the world community.
Philip Goldberg, in charge of coordinating the implementation of sanctions against the North, told reporters in Beijing that he had "very good conversations" with Chinese officials Thursday, though did not give details of the talks.