North Korea test-launched a Taepodong-2 missile early Wednesday along with two short-range rockets, but the long-range missile apparently failed, U.S. officials said.
North Korea's preparations for a long-range missile test have been closely monitored for weeks. A senior State Department official told CNN the Taepodong-2, which some U.S. analysts fear could hit the western United States, appears to have failed in flight.
Military officials told CNN the long-range missile appeared to have failed less than a minute after launch.
Two smaller North Korean missiles were fired from a different site shortly before the larger missile was tested, U.S. intelligence and State Department officials said.
U.S. military sources said those two missiles landed in the Sea of Japan, one closer to Russia and the other closer to Japan.
A senior State Department official said the launches were timed to coincide with the launch of the space shuttle Discovery from Florida, calling it "a provocative act designed to get attention."
Analysts said the tests appeared to have been intended to draw international attention back to North Korea -- and to the stalled talks aimed at convincing Pyongyang to abandon its nuclear weapons program.
North Korea is believed to have the capability to produce several nuclear weapons but has never tested one.
"They are trying to send quite a signal not only to the United States but to the rest of the world that they should be taken quite seriously," said Wendy Sherman, a former State Department official who held talks with North Korean leader Kim Jong Il during the Clinton administration.
Washington and North Korea's Asian neighbors -- South Korea, China, Russia and Japan -- have been trying to persuade North Korea to give up its nuclear program since 2002, but those talks have stalled in recent months.
Jim Walsh, a national security analyst at the Massachusetts Institute of Technology, said the intent of the test appeared to be aimed at drawing attention back to North Korean demands in the six-party talks. But Walsh said the tests "do not represent an immediate military threat to the United States."
"It's very difficult technology. They very clearly have not mastered it," he said. "Most estimates are they will not master it for another 10 years."
The United States, Japan and other countries have warned North Korea against a long-range missile test. The North Koreans fired a Taepodong-1 missile over Japan in 1998, but declared a moratorium on future tests in 1999.
There was no official response to Wednesday's tests from either the White House or from Japan, which had threatened to seek economic sanctions against already-impoverished North Korea if it conducted a missile test.
"One would expect from any administration for there to be sanctions, for there to be a tough response to this," Sherman said.
On Monday, North Korea's state-run media accused the United States of harassing it and vowed to respond to any pre-emptive attack "with a relentless annihilating strike and a nuclear war with a mighty nuclear deterrent."
The White House has dismissed that threat as "hypothetical."
But the U.S. Northern Command increased security measures at its Cheyenne Mountain Air Force Station in Colorado Springs, Colorado, a few weeks ago, a military official confirmed Tuesday.
The base is the seat of the North American Aerospace Defense Command, and some of its command-and-control operations might be used if the United States attempted to use its ballistic missile interceptors to shoot down a Taepodong-2 test.
But a Pentagon official said the missile appears to have failed on its own, without any American effort to knock it down.
In other planning measures instituted in the past several days, Northern Command, along with the Federal Aviation Administration, has put standby commercial flight restrictions into place over Vandenberg Air Force Base in California and Fort Greely, Alaska, where U.S. interceptor missiles are based.
President Bush warned last week that the isolated Stalinist state would face even further isolation if it launched the Taepodong-2, which U.S. analysts fear is capable of reaching the western United States.
"The North Koreans have made agreements with us in the past, and we expect them to keep their agreements," Bush said last month at the end of a European Union summit.
"It should make people nervous when nontransparent regimes, that have announced that they've got nuclear warheads, fire missiles," Bush said. "This is not the way you conduct business in the world. This is not the way that peaceful nations conduct their affairs."