His group observed a tripling of close encounters between the Russian and NATO militaries since the annexation of Crimea in 2014. NATO countries have repeatedly scrambled to intercept Russian bombers, fighter jets and tanker aircraft set on provocative flight paths close to NATO nations' airspace. Footage reported to be that of the downed jet. Credit:Twitter/Habertürk TV "Unfortunately this (shooting down of the Su-24) is not terribly surprising," Mr Kulesa said. Turkey warned in October it would not tolerate any more Russian incursions into its airspace. "This is a very sad confirmation of a problem that was there before."

The situation was still very dynamic, and a lot would depend on emerging evidence of the plane's precise flight path and location. Vladimir Putin's view about who we should deal with in Syria is starting to make more sense. Credit:Bloomberg On Wednesday Reuters reported the United States believed the jet was shot down inside Syrian airspace after a brief incursion into Turkish airspace. A US official, speaking on condition of anonymity, said the assessment was based on detection of the heat signature of the jet.

President Barack Obama said Turkey had the right to defend its borders and air space. He encouraged Russia to focus its attacks on Islamic State to reduce the likelihood of future clashes. Credit:Pablo Martinez Monsivais However "this is getting us back to the darkest hour of the Cold War with the Soviet Union", Mr Kulesa said. "The situation is very grave, it can develop to even more dangerous crisis than it already is." The initial reaction from Russian president Vladimir Putin was "menacing", he said. French President Francois Hollande. Credit:AP The situation is very grave, it can develop to even more dangerous crisis than it already is. Analyst Lukasz Kulesa

"Instead of trying to de-escalate tensions and trying to work to resolve them, he accused Turkey of helping terrorists, and almost of working with ISIS, "This is a very dangerous approach to take. It can very easily escalate further, if they decide to retaliate." Turkey could also escalate the situation, by invoking the NATO treaty and demanding military support from its allies, Mr Kulesa said. "I am sure they want expressions of political support and solidarity, but the question is do they want to go further – would they ask for any operational support, for example early warning aircraft or ground-air missile defence to be deployed?" On the other hand, Turkey may move to de-escalate tensions, believing it has sent enough of a message by shooting down the jet.