Russia said Wednesday that an army colonel working as a military adviser in Syria has died several days after being wounded by rebel shelling in Aleppo. 

Elite Syrian troops moved into east Aleppo Thursday ahead of a push into the most densely populated areas, as regime ally Russia called for corridors to bring in aid and evacuate wounded.

Russia on Monday said its air force was continuing to hold off on strikes against war-ravaged Aleppo, after rebels snubbed Moscow's offer to quit Syria's second city. 

The Russian army on Monday denied any children were present in a school in Syria's Idlib province where 28 people were killed in an October airstrike blamed on Moscow.

Russia has denied having any role in air strikes that the UN children's agency UNICEF said killed 22 students and six teachers at the school in the village of Hass in northwest Syria on October 26.

Nearly half of Russians fear that Moscow's bombing campaign in Syria could spark World War III, a poll showed Monday.

The Kremlin said Friday that President Vladimir Putin did not think it was time to resume air strikes on Aleppo after the defense ministry requested that a moratorium on bombing be lifted.

Russia on Thursday dismissed as "unconvincing" the findings of a UN-led investigation showing that Syrian forces had carried out three chemical attacks, and said no sanctions should be imposed.

"We believe that the proof is not there for any punitive action to be taken. It's simply not there," Russian Ambassador Vitaly Churkin told reporters following a closed-door Security Council meeting. 

Belgium's foreign ministry summoned the Russian ambassador on Wednesday after Moscow claimed Belgian jets from the U.S.-led coalition killed six civilians in airstrikes near Syria's Aleppo, a spokesman said.

Russia warned the U.S.-led coalition Wednesday against driving jihadists from Iraq to Syria, in the offensive to recapture Mosul from the Islamic State jihadist group. 

Police in bullet-proof vests guard a military court for the terrorism trial of Varvara Karaulova, a slim 20-year-old with braided hair who clutches a page of handwritten notes.

Karaulova was studying philosophy at the renowned Moscow State University when she tried to enter Syria last year after falling in love online with an Islamic State fighter.