Japan vowed on Wednesday to shoot down any missiles or rockets fired over its territory after North Korea announced plans to launch a satellite in the coming days.
"Today the defence minister issued an order" to destroy any projectiles if "confirmed that it will fall on Japanese territory", the defence ministry said in a statement.
North Korea on Tuesday informed international organisations of its plans to launch an Earth observation satellite on a rocket between February 8-25. Last month, North Korea announced that it had tested a hydrogen bomb - the reclusive country's fourth nuclear test.
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Al Jazeera's Harry Fawcett said Japan's defence systems were being mobilised for the North's launch, noting Aegis-equipped destroyers were set to sea off Japan's west coast.
"Japan's military has been put on alert. Japan is saying it will - if any parts of this rocket come down in various stages in Japanese territory - they will shoot them down if necessary," Fawcett reported.
South Korea, meanwhile, said Pyongyang will pay a "severe price" if it goes ahead with what the international community sees as a long-range missile test.
In Seoul, the presidential office said North Korea should immediately call off the planned launch, which is a violation of UN Security Council resolutions.
South Korean and US officials said North Korea's move would threaten regional security and violate UN Security Council resolutions that ban the country from engaging in any ballistic missile activities.
"We warn that if North Korea proceeds with a long-range rocket launch, the international society will ensure that the North pays searing consequences ... as it would constitute a grave threat to the Korean peninsula, the region, and the world," South Korean official Cho Tae-yong said in televised remarks.
In Washington, Daniel Russel, the top American diplomat for East Asia, said the US was tracking reports of the North's planned launch.
He said it would strengthen the argument for the international community to impose "real consequences" on North Korea for destabilising behaviour.
North Korea has spent decades trying to develop nuclear weapons along with a missile capable of striking the mainland United States.
North Korea's last long-range rocket launch in December 2012 was seen as having successfully put the country's first satellite into orbit after a string of failures.
Source: Al Jazeera and agencies