This was hashed around on another site, and here is a quote from one of the guys and sounds like a plausible explanation as to why they are being blocked.
From IH8MUD:
As much as I despise Oblama, this story is neither accurate nor fair. The Korean government has been trying to get export approvals so they can sell 100,000 plus surplus U.S. rifles (86,000 garands and 22,000 carbines) to U. S. importers for more than 5 years (long before the Obamunist administration) and have been blocked by U.S. government objections. However, these objections have been based upon the fact the the rifles were loaned by the Defense Dept to Korea, and remain U.S. property. When they became surplus to Korean needs, under the various agreements, the arms were supposed to be returned to the U.S. Army. Instead, the Korean government is trying to sell them to raise some 108 million dollars for their own defense establishment. The stories as to why the U.S. objects (such as the complaint that they might lead to accidents, etc )originated in Korea, not the U.S. and are an attempt by Korea to get past the fact that we still own these rifles, not Korea, and Korea has no legal right to "sell" them to anyone. If the Koreans simply followed the agreement and returned them to the U.S. the rifles would most likely simply be transferred to the Civilian Marksmanship Program (CMP) and sold to U.S. citizens. The Koreans do not want to do this. Korea did get in some diplomatic "hot water" some years back when they illegally sold off some garands to U.S. arms dealers without U.S. government approval (the so-called "Blue Sky" garands). They are trying a end run this time around for a much larger sale.
