North Korea had tested the rocket engines for its intercontinental ballistics missile ahead of the deadly attack on Yeonpyeong Island in 2010, according to a high-ranking source on Sunday.

“In October of last year North Korea tested the rockets for its intercontinental ballistics missile at its Dongchang-ri base,” said the high-ranking government official.

“We believe they conducted the test as a direct show of force when the U.S. satellites could take aerial photos of the site.”

What the government suspected as long distance rocket engines were tested before at the Dongchang-ri base in Cheolsan, North Pyeongan Province, in May and June 2008.

“They have been building the Dongchang-ri missile base since 2001, and although they have completed the launch pad, we believe they still have not finished construction on the entire base,” said the official.

“In order to speed up the construction process, they will need railroads that connect the base with outside facilities to transport components, said another military official.

“We have seen activity that looks like the laying of railroad tracks between the Dongchang-ri base and a nearby station.”

“We do not see any sign of activity that suggests they are trying to fire a missile at the moment,” he added.

The North launched a deadly shelling on a South Korean island of Yeonpyeong near the inter-Korean border Nov. 23, which claimed the lives of two marines and two civilians.

The longest-range North Korean missile under development is the Taepodong-2 missile, presumed to have a range of more than 6,700 kilometers, far enough to hit parts of Alaska, but still incapable of reaching the rest of the U.S.

Both test launches of the Taepodong-2 missile failed. In July 2006, the missile exploded in the air right after liftoff. In April 2009, what it claimed to be a satellite launch also ended in failure after the rocket fell into the Pacific Ocean after traveling about 3,200 kilometers.

By Robert Lee (robert@heraldcorp.com)