Attached Link: http://en.wikipedia.org/wiki/International_Traffic_in_Arms_Regulations

Even though I work for Boeing, I have an idea why Lockheed is asking for removal of said models. It is because of ITAR- International Traffic in Arms Regulations, which classifies how defense related designs, products, and serevices are to be exported. The issue here is that military aircraft designs are controlled by ITAR, and a 3D model is representational of a design. An export is when an ITAR controlled item is brought outside the U.S., when transferred to a foreigner within the U.S., when trasnsferred to a U.S. citizen working for a foreign company in the U.S. By selling a 3D model of an ITAR controlled item on the internet, this constitutes an export. The U.S. State Department has a "blacklist" of restricted contries for trade of defense related items. Someone in a blacklisted country could procure the 3D model and reverse-engineer it, and it could compromise national security. As for commercial aircraft, most are controlled by EAR- Export Administration Regulations. EAR regulations are less stricter than ITAR, although some countries such as Iraq, Iran, Syria, Lybia, and Cuba are still blacklisted. The purpose of EAR is to prevent industrial sabotage, which costs the U.S. billions in lost revenue every year. I hope this helps.