Ukraine has filed a case at the U.N.'s top court accusing Russia of sponsoring "terrorism" and demanding Moscow pay damages for the shelling of civilians and the downing of flight MH17, officials said Tuesday.

Russian officials probing the crash of a Syria-bound military plane said Thursday that there was no explosion on board, but equipment was functioning abnormally when it plunged into the Black Sea.

Turkey and Russia are planning to implement a countrywide ceasefire in Syria before the start of the New Year, Turkish Foreign Minister Mevlut Cavusoglu said Thursday.

President Vladimir Putin has ordered the government to probe the crash of a Syria-bound military plane carrying 92 people including more than 60 Red Army Choir members, the Kremlin said Sunday.

Iran's President Hassan Rouhani and his Russian counterpart Vladimir Putin welcomed the "Syrian army's victory against the terrorists in Aleppo" during a late-night phone call, Iranian media reported on Sunday.

A Russian military plane heading to Syria crashed into the Black Sea on Sunday, with no sign of survivors among the 92 on board, including Red Army Choir members on their way to celebrate the New Year with troops.

The Tu-154 plane went down shortly after taking off from the southern city of Adler where it had been refueling, defense ministry spokesman Igor Konashenkov said in a briefing broadcast on the ministry's website.

Russian President Vladimir Putin said Friday that the economy was set to shrink slightly this year, but by far less than in 2015, as the country struggles out of a two-year recession.

President Recep Tayyip Erdogan on Wednesday said the killer of Russia's ambassador to Turkey was a member of the group of Fethullah Gulen blamed for the July 15 coup, as Moscow warned against jumping to early conclusions.

Russian investigators arrived in Turkey on Tuesday to probe the assassination of Moscow's ambassador as the Turkish government pointed the finger of blame at exiled cleric Fethullah Gulen.

French President Francois Hollande denounced on Wednesday "systematic obstruction" by Russia at the UN Security Council after the failure of a resolution calling for a seven-day ceasefire in the Syrian city of Aleppo.