South Korea, the U.S. and Japan have fully mobilized their surveillance assets as the countries are bracing for North Korea's possible launch of a long-range missile in the near future.

The possibility of North Korea's long-range missile launch is growing after the reclusive country conducted its fourth nuclear test on Jan. 6. North Korea's past nuclear tests have always come with long-range missile launches, although the country has a history of test-firing a long-range missile first, followed by a nuclear test.

United Nations Security Council resolutions prohibit the North from launching long-range missiles which are denounced as being aimed at developing intercontinental ballistic missiles.

"The South Korean military has deployed its Aegis destroyer in the Yellow Sea and given a mission to the early warning and control aircraft 'Peace Eye,'" a government official said.

On the ground, the anti-ballistic radar 'Green Pine' has also started its surveillance operations, the official said.

The Aegis combat system-equipped destroyer is one of the forward deployed surveillance assets of South Korea, with its capability to detect a ballistic missile coming from outside a 1,000-kilometer radius. Within a 500-km radius, the warship's radar could detect and track up to 1,000 targets simultaneously.

It took only 54 seconds for the South Korean Aegis vessel to detect the launch after the North lifted off a long-range missile in December 2012, the latest of Pyongyang's five long-range missile tests.

These are in addition to the U.S.' reconnaissance satellites that keeps watch on North Korea's missile launch sites as well as sea-based radar surveillance assets.

From the side of the U.S. forces stationed in Japan, reconnaissance aircraft called Cobra Ball (RC-135S) is likely to be deployed for the increased surveillance efforts.

Japan has also reportedly set sail one of its Aegis destroyers, JDS Kirishima, which is equipped with SM-3 anti-aircraft interceptor missiles. (Yonhap)