TEHRAN (Press Shia) – Russia said on Tuesday it has delivered an S-300 surface-to-air missile system to Syria.

Defense Minister Sergei Shoigu told President Vladimir Putin during a meeting broadcast by Rossiya 24 TV, “The work was finished a day ago,” adding that the system would improve the security of Russian military personnel in Syria, according to Reuters.

Russia decided to supply the system after Moscow accused Israel of causing the downing of a Russian military jet near Syria in September.

Israel voiced regret at the deaths of 15 Russian aircrew while claiming Syria was at fault.

In Washington, US State Department spokeswoman Heather Nauert could not confirm reports that the S-300 had been delivered.

“I cannot confirm that that is accurate. I hope that they did not,” she told a press briefing. “That would be, I think, sort of a serious escalation in concerns and issues going on in Syria, but I just can’t confirm it.”