Details added (first version posted on 13:14)
Russia will seriously treat the incident with the Su-24 plane and use all means to ensure the security, Russian President Vladimir Putin said, RIA Novosti reported.
Turkish air force shot down Russian Su-24 warplane in Turkey's airspace Nov.24. Both of the pilots managed to eject and the plane crashed on Syria's territory.
"Regarding measures to ensure the safety of flights within the framework of our military operation in Syria, the proposals announced Nov.24 are not enough," Putin told reporters. "We have discussed this in the morning with the leadership of the ministry of defense."
"S-300 anti-aircraft missile systems will be transferred to our military air base in Syria," he said. "I hope that this as well as other measures, since it is not the only measure we will take, will be enough to ensure the flights."
"I would like to say that we are definitely going to treat very seriously what had happened, and all of our funds will be used to provide security," the president said.
Russian Defense Minister Sergei Shoigu, in turn, said that the defense ministry will transfer S-400 advanced anti-aircraft missile systems to the Khmeimim airbase in Syria, where Russian aviation group is based.
"S-400 anti-aircraft missile systems will be transferred to the Khmeimim airbase in Syria," he said at a board meeting of the ministry of defense.