Since early 2017 the U.S. and South Korea have increased their efforts to find out and measure the current status of the North Korea KN-06 SAM (surface-to-air missile) system. American and South Korean intel resources are being directed at North Korean air defenses in general but KN-06 is seen as the most potentially dangerous system. Most of the North Korean air defenses are Cold War era systems but there is some newer stuff and not much is known about that. In particular there is interest in the North Korea KN-06, a clone of the Chinese FT-2000 (which is a clone of the Russian S300). China may have quietly provided some data on KN-06 recently along with other intel on the capabilities of North Korean air defenses.
First noted in 2009 KN-06 was initially believed to be a new ballistic missile using solid fuel. But KN-06 tests in 2009 and later indicated it was probably a homemade SAM. Initial South Korean intelligence analysis of KN-06 said it appeared to be a clone of the Russian S300. Developing such a system would be a stretch for North Korea, but there is a way they could have done it. North Korea and Iran have long been trading technology, and Iran has been buying weapons from North Korea since the 1980s. Iran has also been developing an anti-aircraft missile system with a missile about the same size as the KN-06.
Iran, until 2015, had been prevented from buying the Russian S300 system. For a while Iran looked into buying the Chinese made HQ-9 system. Since 2010 China has been offering its HQ-9 anti-aircraft missile system to foreign customers as the FT-2000. The Russians are not happy with this, given the stolen S300 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. Around 2001 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 also similar to the U.S. "Patriot," while the radar apparently derived much technology from that used in the Russian S300 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.
By 2010 the North Koreans appeared to be testing, as the KN-06, a copy of the HQ-9 missile. At that point North Korea did not have the phased array search radar and the complex guidance system for the KN-06. That may have been taken care of by now because there was a more convincing test of KN-06 in 2016, where it was displayed as a mobile system with a missile that had a max range of 150 kilometers. .
Most of the HQ-9 systems used by the Chinese 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). Just the sort of tech that you could import to North Korea via air cargo, or DVDs full of data. The KN-06 launcher vehicles do not use containers for the missiles and carry only three missiles. Neither the S300 nor HQ-9 have been tested in combat. 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 product's track record, you have to do just the opposite with Russian anti-aircraft missiles. Thus the Russians, and now the Chinese with their FT-2000, emphasize low price, impressive specifications, good test results and potential. China apparently also had special deals that were not publicized and that led to KN-06. The question now is just how effective is KN-06? Not much evidence one way or another. Iran is already complaining that S300 has been “broken” by the Israelis. Whatever the case, you have to keep looking because when it comes to dealing with air defense systems, knowledge is a matter of life or death.