Russia has halved the number of aircraft deployed to its Syria base from the height of its bombing campaign in support of Bashar al-Assad, the military said Wednesday.

A degree of stabilisation in the Syrian conflict "has allowed us to move almost half the air group that was based at Hmeimim back to Russia," said senior commander Sergei Rudskoi at a Moscow security conference, the defence ministry said in a statement.

Rudskoi said that between November last year and January when Russia deployed its only aircraft carrier to carry out strikes, the numbers at Hmeimim base "did not exceed 35 aircraft."

Rudskoi said that despite having "a fraction" of the planes of the US-led coalition, Russia has "carried out three times more sorties" -- more than 23,000 -- and launched "almost four times more air strikes" -- around 77,000.

Defence Minister Sergei Shoigu on Wednesday at the same security conference said Russia's air force was continuing to support Syrian forces in attacking Islamic State (IS) militant group and Al-Qaeda-linked Al-Nusra Front

Shoigu warned that US missile strikes on Syria "created a threat to the lives of our military who are battling terrorism in Syria" and said this forced Russia to take "extra measures to ensure the safety of our personnel."