North Korea says it will send a communications satellite into orbit on a multistage rocket between April 4 and 8. The U.S., South Korea and Japan think the reclusive country is using the launch to test long-range missile technology, and they warn Pyongyang would face sanctions under a U.N. Security Council resolution banning the country from ballistic activity.
Pyongyang's state radio accused U.S. RC-135 surveillance aircraft of spying on the launch site on its northeast coast, according to South Korea's Unification Ministry, which is in charge of monitoring the North.
"If the brigandish U.S. imperialists dare to infiltrate spy planes into our airspace to interfere with our peaceful satellite launch preparations, our revolutionary armed forces will mercilessly shoot them down," the ministry quoted the radio as saying.
It was unclear what capability the North Korea has to shoot down the high-flying Boeing RC-135, which can reach altitudes of nearly 10 miles high. The threat came a day after the North claimed the U.S. and South Korea conducted about 190 spy flights over its territory in March, including over the sea off the launch site.
British Prime Minister Gordon Brown said at a summit Tuesday with South Korean President Lee Myung-bak in London that Pyongyang's launch would breach the U.N. resolution and pledged to respond in step with Seoul, Lee's office said.
Lee, in London for the G-20 summit, told Brown it is important for the international community to show a concerted response to the North's move, his office said. Japanese Prime Minister Taro Aso also urged united action.
In the Netherlands, U.S. Secretary of State Hillary Rodham Clinton warned the North would face "consequences" in the Security Council in the event of a launch.
She also strongly backed Japan's plans to shoot down any incoming North Korean rocket debris, saying the country "has every right to protect and defend its territory from what is clearly a missile launch."
Japan has deployed battleships and Patriot missile interceptors off its northern coast to shoot down any wayward rocket parts that the North has said might fall over the area.
Tokyo has said it is only protecting its territory and has no intention of trying to shoot down the rocket itself, but North Korea said it is not convinced and accused Japan of inciting militarism at home to justify developing a nuclear weapons program of its own.
If Japan tries to intercept the satellite, the North's army "will consider this as the start of Japan's war of re-invasion ... and mercilessly destroy all its interceptor means and citadels with the most powerful military means," the North's official Korean Central News Agency said Tuesday.
The International Crisis Group, a Brussels-based think tank that provides detailed analysis about North Korea — said in a report that the country is believed to have "assembled and deployed nuclear warheads" recently for its medium-range Rodong missiles, which are capable of striking Japan.
But its Seoul-based expert, Daniel Pinkston, said it is unclear if it has mastered the technology necessary to miniaturize the warheads and put them on Rodong missiles, which have a range of 620 to 930 miles (1,000 to 1,500 kilometers).
The group called for a "calm, coordinated" response to the launch, saying overreaction could jeopardize six-nation talks aimed at ridding the North of nuclear weapons programs. Pyongyang has threatened to quit the negotiations if its "peaceful" space program is taken up by the Security Council.
Kim Tae-woo, a missile expert at Seoul's state-run Korea Institute for Defense Analyses, said a recent commercial image shows a round-shaped top at the North's rocket, possibly suggesting it could be a satellite as Pyongyang claims. But he stressed the object could be designed to disguise a missile test.
"It was not shaped like a warhead," Kim said. "But the North can put anything atop the rocket for a missile test as long as it weighs the same as a warhead."
Two U.S. destroyers are believed to have departed from South Korea to monitor the rocket launch. South Korea is also dispatching its Aegis-equipped destroyer, according to a Seoul military official who asked not to be named, citing department policy.
Adding to the complexity of the situation, the North announced Tuesday it will indict and try two American journalists accused of crossing the border illegally from China on March 17 and engaging in "hostile acts."