Iran, desperate for some modern anti-aircraft weapons, has been trying to buy the Russian S-300 system. Blocked from doing that, Iran is now seeking to purchase the Chinese made HQ-9 system. This could get interesting. Earlier this year, Russia admitted that, two years ago, they signed a contract to sell S-300 anti-aircraft missile systems to Iran. The S-300 has not been delivered because Western nations have told Russia and China that if they arm Iran with modern weapons, there will be consequences. China has an incentive to back off here, because a stronger Iran threatens China's oil supplies. Russia, however, would benefit by Iranian attempts to shut down oil shipments from the Gulf (if only temporarily, to make a political point), as the price of oil would shoot up, to the benefit of Russian oil sales.
Until recently, it was all rather murky as to why Russia was not delivering those S-300 systems to Iran. There were mixed messages, with Iran indicating that it was getting S-300s, and Russia denying there was any deal. What was happening was that Russia was obviously holding off, while squeezing more and more favors and concessions out of the West. Iran is not happy about not getting its missiles, but Iran doesn't have the clout to force the sale to happen. How the recent Russian admission, that the deal exists, fits into all this is unclear. It probably has to do with what concessions Russia hopes to get out of the West, and the United States in particular. Russia has a long list of desired concessions. For one, Russia does not want the United States to go forward with installing an anti-missile system in Poland and the Czech Republic. Russia also does not want any more nations on its borders joining NATO. So the haggling continues, even as it emerges from the shadows.
Meanwhile, China has begun offering its HQ-9 system to foreign customers, as the FD-2000. The Russians are not happy with this, given the stolen S-300 technology in the HQ-9. Russia has been pointed in warning China not to export weapons containing stolen Russian tech. But the Chinese have done it, apparently believing there's really nothing the Russians can do about it. But in this case, the Russians can just ship the long promised (and partially paid for) S-300s to Iran.
A decade ago, China began introducing the HQ-9 for use by its army and navy (on ships). Over a decade of development was believed to have benefitted from data stolen from similar American and Russian systems. The HQ-9 missile is similar to the U.S. "Patriot," while the radar apparently derived much technology from that used in the Russian S-300 system. The HQ-9 missile has a max range of about 100 kilometers, weighs 1.3 tons and has a passive (no broadcasting) seeker in the missile.
Most of the systems used by the army are mobile. Army HQ-9 brigades have a brigade headquarters (with a command vehicle, and four trucks for communications and maintenance), six battalions (each with a missile control vehicle, a targeting radar vehicle, a search radar vehicle and eight missile-launch-vehicles, each carrying four missiles in containers).
Neither the S-300 or HQ-9 have been tested in combat. Most earlier Russian designed air defense systems performed poorly in combat. Even the Russian SA-6 missile systems, that Egypt used in 1973, which were initially a surprise to the Israelis, were soon countered, and did not stop the Israelis from getting through. While the best sales technique is to push the products track record, you have to do just the opposite with Russian anti-aircraft missiles. Thus the Russians, and now the Chinese with their FD-2000, emphasize low price, impressive specifications, good test results and potential.