Thanks to Russian President Vladimir Putin, rebel-controlled areas of eastern Ukraine where Malaysia Airlines flight MH17 crashed are now awash with powerful anti-aircraft missiles that pose as much of a threat to civilian airliners as they do to military aircraft. Despite his denials to the contrary, Putin has been steadily increasing his support for pro-Russian rebels as he attempts to force Ukraine to abandon its attempts to forge closer links with the European Union (EU). Only last Sunday, while the Russian president was attending the World Cup final in Brazil, a 150-strong armoured column, including tanks, armoured personnel carriers and missile launchers was reported to have crossed the Russian border and entered Ukraine in the disputed Luhansk region of eastern Ukraine, prompting the Ukrainian government to issue a formal complaint.

There are strong indications that the convoy included launchers for the Russian Buk missile system that has the range to shoot down civilian airliners. At about the same time as the Russian convoy was crossing the Ukrainian border last Sunday night, Putin was reassuring Angela Merkel, the German Chancellor, that he was seeking a peaceful resolution to the Ukraine crisis. However, there has been a marked build-up of sophisticated Russian weaponry since Ukraine last month signed an association agreement with the EU, which senior Kremlin officials at the time warned would have “grave consequences”.

An indication of the powerful weaponry Russia is now providing the rebel factions was demonstrated last Monday when pro-Russian forces managed to shoot down a Ukrainian AN-26 military transport aircraft, killing the 19 military personnel on board, which was flying at a height of 21,300 feet. As Ukrainian officials commented after the incident, the precision used to carry out the attack using sophisticated anti-aircraft missiles was well beyond the ability of most untrained rebel fighters. And, just hours before the Malaysia Airlines flight crashed, tensions between Moscow and Kiev had risen further after the Ukraine government accused Russia of shooting down one of its Su-25 ground-attack jets.

The rebels, meanwhile, claimed they had shot down two Ukrainian jets on Wednesday, and another on Tuesday. In such a frenzied atmosphere, where the normal strict controls are not always applied to powerful weapons, there is always the possibility of a tragic accident occurring, especially when civilian aircraft are operating close to the scene of hostilities. According to Ukrainian officials, the Malaysia Airlines flight was cruising at around 32,800 feet, whih was 11,500 feet higher than the Ukrainian transport aircraft — at the time of the incident.

And on Thursday, they were pointing to the possibility that an anti-aircraft missile that can shoot down a plane at 21,300 feet can also shoot one down at 32,800 feet. There have certainly been some notable instances when civilian aircraft have been shot down accidentally when straying into hostile territory. In 1983, at the height of the Cold War, Soviet war planes shot down Korean Airlines flight 007, killing 269 people after it strayed into Soviet airspace. Then in July 1988, the American naval vessel USS Vincennes shot down Iran Air flight 655, killing 290 passengers and crew after it mistook the aircraft for an enemy missile. Many experts believe the Lockerbie bombing, when Pan Am flight 103 was blown up in mid-air, killing 270 people, was a revenge attack.

It is still too early to say for sure whether Russia’s arms build-up in Ukraine was to blame for Thursday’s disaster, but the fact that it is no longer safe for any form of aircraft to fly in the region should be a wake-up call to the outside world to pressure Putin to call a halt to his irresponsible meddling in Ukrainian territory.

Earlier last week, Washington unilaterally increased economic sanctions against Moscow. If ultimate responsibility for the Malaysia Airlines crash falls on Russia, then we can expect far tougher action to be taken.

— The Telegraph Group Limited, London, 2014