With mounting evidence that Malaysia Airlines Flight MH17 was shot down by Ukrainian separatist rebels who believed they were engaging a military aircraft, attention is focusing on the Russian-built Almaz-Antey Buk-M1 ground-based air defense system (GBADS) that destroyed the airliner.

The Buk-M1 (SA-11 Gadfly to NATO) can be used by minimally trained operators to deliver a lethal attack, without the safeguards built into other comparable GBADS, an Aviation Week analysis shows. It is also one of the two GBADS — both of Soviet origin — that are most widely distributed in conflict zones with the potential for large-scale, cross-border or civil violence.

The feature that makes the Buk-series weapons uniquely dangerous was introduced in the 1970s when Tikhomirov NIIP, now part of Almaz-Antey, designed the system to replace the 2K12 Kub low-altitude missile system, known to NATO as the SA-6 Gainful. (The similar names are coincidental: "Kub" means "cube" and "Buk" means "beech.")

Kub was exported to Egypt after the destruction of that nation’s air force in a low-level air strike in 1967, and proved lethal in the 1973 Yom Kippur war. But it had a serious weakness in that it could engage only one target at a time. A Kub battery included one radar vehicle and four launch vehicles and used semi-active radar homing (SARH) guidance. The radar vehicle carried two antennas, a search radar and a continuous-wave tracker-illuminator, and the missile homed on to energy from the illuminator beam that was reflected from the target. With one illuminator per battery, the system could not start a second engagement until the previous missile had hit the target.

In the 1982 Lebanon war, the Israel Defense Force – Air Force launched a wave of decoys against Kubs and other GBADS. Once the Kubs locked onto the decoys they were unable to respond to the IDF-AF fighters that appeared next, and were destroyed.

The designers of the replacement Buk system had anticipated this problem. In addition to a new radar vehicle – the Phazotron 9S18M, Snow Drift to NATO – they fitted each launch vehicle with its own X-band multi-mode radar, under a radome on the front of the rotating launch platform. The vehicle is defined as a transporter/erector/launcher and radar (Telar). Similar to a fighter radar, the Telar radar (known to NATO as Fire Dome) has search, track and illuminator functions and can scan through a 120-deg. arc, independent of the movement of the platform.

This feature may have been a crucial factor in the destruction of MH17. The Fire Dome radar’s main job was to permit simultaneous engagement of more targets – one per Telar – under control of the battery’s 9S18M Snow Drift. But the Soviet military and the designers installed a set of backup modes that would permit the Telars to detect and attack targets autonomously, in the event the Snow Drift was shut down or destroyed by NATO’s rapidly improving anti-radar missiles.

The autonomous modes are intended for last-ditch use by the Telar operators, not the more highly trained crews in the battery command vehicle. According to an experienced analyst of Russian-developed radar, the automatic radar modes display targets within range. The operator can then command the system to lock up the target, illuminate and shoot.

Critically, these backup modes also bypass two safety features built into the 9S18M Snow Drift radar: a full-function identification friend-or-foe (IFF) system and non-cooperative target recognition (NCTR) modes. The IFF system uses a separate interrogator located above the main radar antenna and most likely will have been upgraded to current civilian standards.

The 9S18M introduced new NCTR processing technology, according to a 1998 interview with Buk designer Ardalion Rastov. NCTR techniques are closely held, but one of the most basic – jet engine modulation, or the analysis of beats and harmonics in the radar return that are caused by engine fan or compressor blades – should easily discriminate among a 777 with high-bypass turbofans, a turboprop transport or an Su-25 attack fighter.

There is no sign of an IFF interrogator on the Buk Telar’s Fire Dome radar or elsewhere on the vehicle. In normal operation, it would not be necessary since the target’s identity would be verified (according to the prevailing rules of engagement) before target data was passed to the Telar. Other GBADS also leave identification to the main search radar and the command-and-control center; however, the launch units cannot engage and fire without central guidance. The Buk’s combination of lethality and lack of IFF/NCTR is unique.

The Buk-M1 and later derivatives, the M2 and M2E, have been deployed in 14 nations, and are operational in other areas subject to internal conflict. In January 2013, Israel launched an air strike that was apparently intended to destroy a number of Buk-M2E vehicles – the more advanced version – that were being transferred from Syria to Hezbollah forces in Lebanon. In all, Syria is reported to have possessed eight Buk-M2E batteries. Syria also operates as many as 40 S-125 (SA-3 Goa) batteries, which are reportedly being upgraded. These also are medium-range, mobile weapons, but the launch units do not have radar. The same goes for the nation’s aging Kub batteries.

Egypt has 50-plus batteries of S-125, some of which have been modernized, and has been reportedly negotiating orders for Buk-M2E systems. Yemen also has some S-125 systems. Most pre-2003 Iraqi and Libyan GBADS have been destroyed, analysts suggest.