Russia has blamed Israel after one of its reconnaissance aircraft carrying 15 people was shot down by a Syrian surface-to-air missile over the Mediterranean Sea.
There are not believed to have been any survivors.
The Russian military said the Il-20 reconnaissance aircraft was accidentally hit by a Syrian missile which had been aimed at four Israeli fighter jets that were attacking targets in the coastal province of Lattakia late on Monday.
Russia said the Israeli aircraft “pushed” the Russian plane into the line of fire and accused the Israeli army of “intentional provocation”. Russia said it would make an “appropriate response”.
“The Israeli pilots were using the Russian aircraft as a shield and pushed it into the line of fire of the Syrian defense,” defence ministry spokesman Major General Igor Konashenkov said in a statement.
Russia said Israel did not warn it of its operation in the area until one minute before the strike.
For several years, Israel and Russia have maintained a special hotline to prevent their air forces from clashing in the skies over Syria. Israeli military officials have previously praised its effectiveness.
Russia has been a key backer of Syrian president Bashar Assad and it has two military bases in the country, including one close to the Mediterranean coast.
The Israeli military said earlier on Tuesday that it had no reaction, saying it does not comment on “foreign reports.”