President Vladimir Putin said on Tuesday that the shooting down of a Russian military plane near Syria's sea coast was the result of a chain of tragic and chance circumstances.

Russia's Defense Ministry said earlier that the aircraft was shot down by Syrian anti-aircraft systems, but accused Israel of indirectly causing the incident, saying Israeli jets operating nearby had put the Russian plane in the path of danger. The ministry threatened to retaliate over what it called a hostile act.

Putin's comments, made after talks with Hungary's prime minister in Moscow, appeared to somewhat defuse the situation though he said Russia needed to look further into what happened.

"It looks most likely in this case that it was a chain of tragic chance events, because an Israeli aircraft did not shoot down our aircraft. But, without any doubt we need to seriously get the bottom of what happened," Putin told reporters.

The Russian president said Moscow's response to the incident would aim at securing the safety of Russian military personnel in Syria's complex civil war in which various outside powers have backed opposing sides.

"As for retaliatory measures, they will be aimed first and foremost at further ensuring the safety of our military personnel and facilities in Syria. And these will be steps that everyone will notice," Putin said.

Russia's Defense Ministry said the Il-20 reconnaissance aircraft, with 15 Russian service personnel on board, was brought down by anti-aircraft batteries of Moscow's ally, Syria, in a "friendly fire" incident.

But the ministry said it held Israel responsible because, at the time of the incident, Israeli fighter jets were mounting air attacks on Syria targets and had only given Moscow one minute's warning, putting the Russian aircraft in danger of being caught in the cross-fire.

"We view the actions of the Israeli military as hostile," Russian Defense Ministry spokesman Igor Konashenkov told Russian state television. "As a result of the irresponsible actions of the Israeli military, 15 Russian service personnel perished."