South Korea’s Ministry of National Defense said on Friday that the country and its U.S. ally have been sharing intelligence and tracking down potential North Korean facilities used to develop highly enriched uranium for nuclear weapons.

“South Korea and the U.S. have been identifying HEU facilities in North Korea by analyzing intelligence images,” said a South Korean army intelligence official.

He added, “We are currently tracking down those facilities and activities relating to HEU,” as the allies have not yet made a final judgment call whether they are for nuclear weapons development.

This comes as the Defense Ministry released its 2012 Defense White Paper on Friday on the security situation on the Korean Peninsula for public understanding.

North Korea is speculated to hold about 40kg of plutonium, and the communist state disclosed its uranium centrifuges in 2010, according to the White Paper.

After firing its long-range rocket, or missile, on Dec. 12, defense experts and officials suggest that it could be moving to test a nuclear weapon as it did in 2006 and 2009.

It test-fired a nuclear weapon in Oct. 2006 after it launched a long-range missile in July the same year. Its second nuclear test occurred in May 2009 after firing a missile in April 2009.

Uranium has a more powerful nuclear blast than plutonium, but it is much more difficult to develop weapons from as it holds very little U-235 isotope needed for fission.

The Defense Ministry also noted that it is closely monitoring signs of North Korea expanding its air and surface landing infiltration capabilities toward South Korean islands, including Yeonpyeong, in the West Sea where the country has been vulnerable to North Korean provocations.

North Korea has around 300 helicopters and 260 hovercrafts and high-speed landing ships.

The 2012 White Paper continued to brand North Korea as South Korea’s enemy, and clearly marked the country’s Northern Limit Line on a map, and stated that it will protect its territory south of the NLL, which is the “real” inter-Korean maritime border with the North.

Also, Defense Ministry officials reiterated its White Paper position on Dokdo, saying that Dokdo is “geographically, historically and legally” South Korea’s territory, and it will protect it at all cost from Japan.

By Park Hyong-ki (hkp@heraldcorp.com)