A naturalized American citizen, Yi Qing Chen, was recently sentenced to 25 years in prison for smuggling drugs, cigarettes and Chinese QW-2 shoulder fired surface-to-air missiles into the United States. Similar to the U.S. Stinger, the QW-2 is built under license by Pakistan and Iran. The missiles never made it out of China, because Chen was arrested before that part of the deal could be completed. Chen was also the first person prosecuted (and given the mandatory 25 year sentence) under a 2004 law dealing with attempting to smuggle such missiles into the United States.
Chen offered to get 200 of the QW-2 missiles, for $91,500 each, and deliver them to anywhere in southern California. Chen also described how he would bribe customs inspectors in the United States and arrange for phony purchase orders from the armed forces of another country, so the missiles could be bought and shipped from China (where he had contacts with the manufacturer who would go along with all this).
While many criminal organizations around the world (like the Taliban, African warlords and South American drug gangs) have obtained and used missiles like this, it's been very difficult to get these weapons into the United States. This is partly out of self-interest. Commercial aviation is used by just about everyone, and American law enforcement agencies at all levels let it be known that anyone reporting attempts to sell such missiles would be well rewarded. Thus there have been no incidents of such missiles being used in the United States, but there have been many arrests of people attempting to traffic in these weapons (which are compact, and weigh less than 20 kg/44 pounds). But the danger is there, as such weapons have been used by gangsters, rebels and terrorists in South American, Asia and Africa.