Russia will not ship the advanced S-300 anti-aircraft missile system to Iran, a top Russian official said during a weapons exhibition in Rio de Janeiro on Wednesday. Alexander Fomin, deputy head of the Federal Service for Military-Technical Cooperation, said "at the moment nothing is happening and there are no shipments" of the advanced system to Iran. However, Fomin was also quoted by AFP as saying that "military-technical cooperation between Russia and Iran has a positive influence on stability in this region." He did not elaborate when, or if, the shipment would be delivered. A deal to sell the S-300 was sealed several years ago, but Moscow has yet to deliver the system. Some Western analysts remain skeptical and believe the system has not only been delivered but already deployed. The US position is that the system is not yet in Iran. Iran's Press-TV reported Wednesday that Moscow has recently delivered 29 Russian-made Tor-M1 air defense missile systems to Iran under a $700 million contract signed in late 2005, and has trained Iranian Tor-M1 specialists, including radar operators and crew commanders. The Tor-M1 system, known in the West as SA-15 "Gauntlet," is an all-weather low to medium altitude, short-range surface-to-air missile system designed for engaging aircraft, cruise missiles, precision guided munitions and ballistic targets. It is the first air defense system in the world designed from the start to shoot down precision guided weapons. The system was developed in the mid 1970s. Israeli security officials have said in the past they see the delivery of the S-300 as a threshold for Iran's nuclear program, as procurement and deployment of the system by Iran would vastly complicate any potential Israeli air strike on Iran's nuclear targets. The S-300 is considered the most advanced system of its kind in the world today and is capable of simultaneously engaging multiple targets over a vast range. Israel has been exerting heavy pressure on Russia not to proceed with the sale of the system to Iran.