North Korea could launch a long-range missile as early as Sunday, a respected Japanese newspaper reported, citing unnamed government sources, While North Korea accused the United States of conducting spy flights on "strategic targets" along its east coast.
The Japanese newspaper Sankei Shimbun also said Japan has dispatched two Aegis destroyers to the Sea of Japan and the Pacific Ocean.
Also Saturday, South Korea's Chosun Ilbo newspaper said the North loaded booster rockets onto a launch pad and moved about 10 fuel tanks to a launch site in preparation to test-fire the missile.
South Korea and the United States made the assessment after analyzing satellite images for the past few days, Chosun Ilbo reported, citing an unnamed high-level South Korean government official.
The RC-135 reconnaissance aircraft "spied on its (the North's) strategic targets for hours," off the east coast on Friday, said an air force statement carried by the North's Korean Central News Agency.
The communist state has issued similar statements twice in recent days, claiming that the U.S. is stepping up its aerial espionage missions in preparations to attack the country.
"Should those planes persist in their reckless air espionage ... they will not be able to escape the same end as that of a tiger moth fated to perish in the flames and the responsibility for that will wholly rest with the U.S. imperialist warmongers," the North's statement said.
North Korea routinely accuses the U.S. of conducting spy flights, issuing a tally of such flights at the end of every month. The U.S. military doesn't comment, although it acknowledges monitoring North Korean military activity.
The reports come as the U.S. government warns that communist state is accelerating preparations for testing a missile that has the potential to strike the U.S. mainland.
There is no law against the test, so the United States cannot do much to stop it. The North Koreans have undoubtedly thought through the consequences and, as one expert said, they must have decided relations with the United States cannot get any worse, CBS News correspondent David Martin reports.
While the Bush administration has focused most of its recent attention on Iran's nuclear programs, many arms professionals insist the North Koreans pose a more immediate challenge.
"There is nothing more lethal than a country like North Korea having a long-range intercontinental ballistic missile with a nuclear warhead on it," Wendy Sherman, former adviser to President Clinton on North Korea, told Martin.
Sherman thinks North Korea's actions are an attempt to grab attention, saying they want "to make people to understand that they not only have this technology but they've shared this technology with many countries around the world, including Iran."
Officials in Japan and the United States have said that the North Korean government appears to be stepping up preparations to test a long-range Taepondong-2 missile and that a test may be imminent. Such a missile could potentially reach parts of the United States.
"They probably increased their nuclear arsenal by six to eight weapons while President Bush has been in office," said Michael O'Hanlon, a national security analyst at the Brookings Institution. "And, meanwhile, Iraq and Iran have made a grand total of zero weapons."
North Korea tested an earlier version in 1998 and it caused a worldwide uproar.
That missile flew over Japan, but its third stage failed to ignite and pieces plunged into the northwestern Pacific Ocean. Now, Western experts fear North Korean engineers have improved the technology.
Mr. Bush famously linked North Korea, Iran and prewar Iraq as an "axis of evil" in his January 2002 State of the Union speech. But the weapons of mass destruction Mr. Bush claimed Saddam Hussein possessed were never found. And Iran is not believed to have any nuclear weapons, although its uranium enrichment program is the center of intense attention.
Iran insists its nuclear program is for generating electricity and not making weapons. North Korean officials, by contrast, boast they already have the atomic bomb.
State Department spokesman Sean McCormack said Friday that the United States and its allies have "made clear to North Korea that a missile launch would be a provocative act that is not in their interests and will further isolate them from the world."
Such a launch would be inconsistent with a moratorium on tests declared by North Korean President Kim Jong Il in 1999 and renewed in 2002, McCormack said. Still, North Korea has tested many short-range missiles, two as recently as March.
White House national security adviser Stephen Hadley said this week it would be a "bad idea" for North Korea to test a long-range missile and urged Pyongyang to return to arms negotiations.
But those talks, among North and South Korea, China, Japan, Russia and the United States, have been stalled for months. The most recent meeting was in November. A dispute over U.S. allegations of North Korean counterfeiting of U.S. currency is contributing to the impasse.
In moving toward missile tests, North Korea may just be saber rattling. But the menacing gestures could make it even harder to get the six-nation talks restarted.
"If North Korea conducts tests, it is unlikely the talks will resume anytime soon," said Daryl Kimball, executive director of the Arms Control Association.
"The Bush administration has failed to seize the opportunity that has presented itself for some time with North Korea to negotiate a solution to the nuclear crisis and to do many of the same things it is now proposing to do with Iran," said Kimball.
"Kim Jung Il must wonder why such a package has been put on the table for Iran when Iran doesn't even have a nuclear weapon yet," Sherman tells Martin.
"While North Korea continues to develop its ability to attack the United States, our negotiating leverage decreases," Democratic Sens. Carl Levin of Michigan and Hillary Clinton of New York wrote in a joint letter to Mr. Bush on Friday. They urged him to develop a single strategy for dealing diplomatically with North Korea and to appoint a senior envoy to carry it out.