The prime suspect behind the MH17 tragedy is the self-proclaimed defence minister of the Donetsk People's Republic, Igor Girkin.

According to the Sydney Morning Herald , the former intelligence officer is known by the name Strelkov - or "shooter" and has even shot his own troops for insubordination.

The spotlight fell on Girkin ( left ) after he reportedly posted a message on a Russian social media page, which read: "We did warn you - do not fly in our sky."

The post was later removed when it became clear that the plane was a civilian aircraft and not a Ukranian military plane.

The Sydney Morning Herald pointed out that "no amateur can bring down a passenger jet streaking across the sky."

"Don't be lulled into believing any trooper with a rocket-propelled grenade launcher on his shoulder could carry out this attack.

"The professionalism required points to Girkin and his Russian-backed separatists as the most likely suspects.

"They have captured missile batteries mounted on trucks, and are suspected to have been supplied with Russian-made 'needle' portable launchers that can be carried by a man," reads the report.

As Ukraine and pro-Russian separatists blamed each other for the crash of MH17 Boeing 777, a sophisticated missile system has been brought into the public limelight – the Russian-made 9K37 Buk.

Confirmation that a missile was involved will only come if someone admits firing one, or if crash investigators find shrapnel and other tell-tale signs on the aircraft debris and the bodies recovered.

Nevertheless, the use of a missile was raised soon after the MH17 disaster by a Ukrainian Interior Ministry official who said pro-Russian forces had used the missile to bring down the plane.

However, the self-proclaimed Donetsk People’s Republic has denied having missiles in its possession.

A medium-range surface-to-air missile such as Buk is necessary to bring down an aircraft at a cruising altitude as shoulder-fired missiles (called Manpads, or Man-Portable Air Defence System), favoured by insurgents worldwide for their portability, lack the range needed.

Manpads can only threaten commercial airliners during take-off and landing, when it is flying relatively low and slow. The earliest version of the Buk missile has a maximum engagement altitude of 14 kilometres. The MH17 was reportedly flying at about 33,000 feet (10km) high.

Airspace MH17 was in was deemed 'open'

According to a report in British newspaper The Guardian , the Ukrainian authorities had banned flights at 32,000ft (9.75km) and below in the area where MH17 crashed at the time of the incident, and the airspace it was flying was deemed "open". That airspace in eastern Ukraine is now closed to all civilian air traffic.

The radar-guided missile weighs just over half-a-tonne and is typically launched from the top of an armoured vehicle or a ship, in contrast to Manpads that can be carried and fired by a single person and are designed to attack low-flying aircraft and helicopters.

Various versions of the missile, carrying nicknames such as "Grizzly" and "Gadfly", have been fielded since 1979 in Russia, Ukraine, China and other countries.

It had seen combat on both sides of the 2008 South Ossetia war between Russia and Georgia, during which defence analysts noted the Russian Air Force had taken heavy casualties relative to the small Georgian military and could not develop an effective counter-measure against a missile system it created.

However, the question remains: If a missile brought down the MH17, who fired it?

"It's a very capable system, proven under real-world conditions," Foreign Policy magazine quoted a political risk consultancy Wikistrat researcher Andrew Bowen as saying, while noting that the system is difficult to use.

"These systems require a large amount of technical know-how, unlike these Manpads, which are basically 'point-and-shoot'," Bowen said.

Foreign Policy also reported that Ukraine has such missiles in its possession. However despite denials, so does Donetsk, which is said to have a missile system similar to Buk.

Donetsk had acquired Buk missiles, says report

The magazine quoted Russian newswire Itar-Tass as reporting on June 29 that Donetsk had acquired Buk missiles, and said the group had even bragged about its acquisition on Twitter.

The posting, also dated June 29, has since been removed and can only be viewed via Google’s cache.

"An Associated Press reporter spotted what was described as 'a launcher similar to the Buk missile system' near the town of Snizhne.

"On Thursday, a Twitter account associated with Maidan protest movement in Kiev posted a photograph purporting to show a Buk launcher in the town of Torez, which is near the crash site and has been the scene of fighting between separatist and government forces," the report added.

The report also noted that while Ukraine does have Buk missiles near the crash site, these missiles in the region were only used against Ukrainian government aircraft.

Meanwhile, deputy editor of the Polish magazine Dziennik Michal Potocki, who had been studying the conflict in Ukraine, agreed that the separatist group is responsible for shooting down the Malaysian airliner.

"It cannot be the Ukrainian side - they do not need to use surface-to-air missiles as the separatists do not have airplanes as for now. It was probably a missile system called Buk," Potocki told Malaysiakini in an email today.

He also pointed out that just before news broke that MH17 had crashed, separatist leader, Igor Strelkov, posted on a Russian social media site that two supposedly Ukrainian aircraft had been shot down, saying that they were "an Antonov and probably a Sukhoi".

"Only after we got the news that it was Boeing - the separatists started to blame the Ukrainian side," Potocki said.

MH17 had been using a Boeing 777-200ER aircraft for the Amsterdam-Kuala Lumpur flight, which is the same model used for flight MH370 that went missing on March 8.

All 295 on board perished in the incident.