Moscow on Tuesday blamed Israeli fighter jets for “using a Russian plane as cover” during a Monday night raid in Syria, sparking a deadly shoot-down of a Russian aircraft by its Syrian allies.

“The Ilyushin-20, its reflective surface being far greater than that of the F-16, was downed by a missile launched with the S-200 system,” Russian Defense Ministry Spokesman Igor Konashenkov said, referring to the Soviet-era air defense system.

Fifteen military personnel were killed in the attack, the defense ministry said. Russian naval ships are now working to retrieve the bodies, personal belongings and the plane’s debris in the Mediterranean Sea off the Syrian coast, TASS reported.

According to Konashenkov, the Israelis had given Russia “less than one-minute” warning before the 10 pm strike on Latakia province, where Russia has a base.

The Israeli military on Tuesday said its planes were already back in Israeli airspace when the Russian plane came under attack and blamed the Syrian army for “extensive and inaccurate fire.”

“Israel will share all the relevant information with the Russian Government to review the incident and to confirm the facts in this inquiry,” the Israeli military said via Twitter.

Russia’s defense minister rejected the Israeli assessment.

“Israel struck at Syria using the Russian Il-20 as cover, thinking Syria wouldn’t strike back,” Sergey Shoigu said, notifying his Israeli counterpart that “Russia will not leave the actions of Israeli air force in Syria unanswered.”

Russian President Vladimir Putin, offering his condolences to the families of the servicemen, appeared to tone down that threat, saying the Il-20 crash was due to “tragic accidental circumstances.”

Retaliation, he said, would be in the form stronger safety measures for military personnel in Syria and a reinforcement of Russia’s military positions.  “It will be something everyone will notice,” Putin said.