U.S. federal agents arrested a Belgian man, Jacques Monsieur, in New York, and charged him with attempting to buy jet engines, and other aircraft spare parts, on behalf of Iran. Monsieur, and his partner, Iranian Dara Fotouhi, were seeking the equipment for Irans, 1970s era, F-5 jet fighters. Monsieur has worked with the Iranians for years, although he was jailed in Iran at one point, and accused of spying for the United States. The smugglers are out for a buck, and Iran pays well. But sometimes, so does the CIA and FBI, and the Iranians know it (and have been double crossed by some of their smugglers).
Ever since the U.S. embargo was imposed in 1979 (after Iran broke diplomatic protocol by seizing the American embassy), Iran has sought, with some success, to offer big money to smugglers who can beat the embargo and get needed industrial and military equipment. This is a risky business, and American and European prisons are full of Iranians, and other nationals, who tried, and often failed, to procure forbidden goods. The smuggling operations are currently under more scrutiny, and attack, because of Iran's growing nuclear weapons program. But the Iranians simply offer more money, and more smugglers step up to keep the goodies coming.
The U.S. has gotten more aggressive, and successful, at shutting down Iranian smuggling operations. Not just by bribing the smugglers themselves, but also by getting the cooperation of nations the smugglers operate out of. This has been so successful that most of these smugglers no longer feel safe working out of Arab Persian Gulf nations (especially the United Arab Emirates). As a result, more smugglers are operating out of Malaysia, and the U.S. is trying to shut down that activity. America also monitors the international banking network, seeking signs of smuggler activity, and leaning on the banks involved, to step back.