The threat by Venezuelan dictator Hugo Chavez selling 21 of Venezuela's F-16 fighters to Iran, has gained press attention. However, this is a threat that is largely empty in terms of potential harm to the United States.
The F-16s in question were acquired in 1983 and 1984, and are technically the F-16A/B Block 15 (F-16s currently in service with the US Air Force are F-16C/D Block 50s, with the F-16E/F Block 60 being built for the UAE). The planes in question are twenty years old - and for the F-16, that is very old indeed. These aircraft are not equipped with the latest radars, air-to-air missiles, or jammers. And, in the eight years since Chavez took power, they have not been getting much in the way of logistics thanks to the freeze in relations (upsetting the country which makes the spare parts for your combat aircraft is not a good idea).
That said, Chavez's threat to sell them to Iran is meant to generate headlines, and to symbolically hurt the United States. But this move, while it would violate various export agreements, really will not hurt the United States militarily, even if Iran were to get all 21 of these F-16s. The planes would be going from a country with very limited logistical support ability for the F-16 (Venezuela) to one with practically no ability to support F-16A operations at all.
For instance, none of Iran's planes currently in service use the Pratt and Whitney F100 engine that the Venezuelan planes use. Nor does Iran have any aircraft that use the APG-66 radar on the F-16A. Iran could use rear-aspect Sidewinders from its F-5 force, along with 20mm cannon ammo from its force of F-4s, but when something on the airplane breaks, Iran will have to cannibalize, and that means that 21 F-16s will quickly drop to a much lower figure - as past experience with Iran's force of F-5s, F-4s, and F-14s has shown. Venezuela could send over what spare parts and missiles (including older all-aspect AIM-9L Sidewinders), but the missiles will have a finite shelf life. Expired missiles are generally unhealthy for people who try to use them.
In other words, if Chavez is able to sell the planes to Mahmoud Ahmadinejad's regime in Iran, he will have sold 21 planes which will rapidly become a world-class maintenance and logistical headache for their new owners. But they will not be Chavez's logistical headache, and he can use the proceeds from the sale to, at a minimum, defray the cost for new fighters from Russia or China. - Harold C. Hutchison (email@example.com)