Captain Alexander Shvarts watched on as the iron covers whirred open on the air defense system aboard the Russian navy's Mosvka missile cruiser off the Syrian coast.

"This system can fire up to twelve missiles at any one time," Shvarts said Thursday during a highly choreographed press tour of the ship arranged by the Russian defense ministry. "The range is around 70 kilometers (43 miles)."

Senior international envoys began gathering in New York on Thursday to seek U.N. backing for an ambitious U.S. and Russian plan to seek a negotiated ceasefire in Syria's brutal civil war.

U.S. Secretary of State John Kerry has already traveled to Moscow this week to assure Bashar Assad's key Russian ally that Washington is not seeking "regime change" in Syria.

US Secretary of State John Kerry met Russia's President Vladimir Putin at the Kremlin on Tuesday to seek agreement on how best to push forward efforts to halt Syria's brutal civil war.

Russia and the United States are sponsors of an international effort to broker a ceasefire and political talks between Bashar Assad's regime and Syria's armed opposition.

A Russian court on Tuesday sentenced a Ukrainian man to 11 years in prison on espionage charges, after he was accused of buying "state secrets" concerning Russia's aerospace industry.

The verdict against Valentyn Vygovskiy, described in the media as a 32-year-old businessman, was swiftly condemned by Kiev, with foreign ministry spokeswoman Maryana Betsa calling it "illegal".

Poland's foreign minister on Tuesday accused Germany of putting Russia's interests above the security of eastern Europe, saying Berlin had neglected to show solidarity with its neighbors.

Retorting sharply to accusations against Warsaw over its refusal to shoulder a bigger share of refugees streaming into Europe, Witold Waszczykowski instead questioned Germany's stance on eastern Europe.

A Russian-run energy company in Crimea said on Monday a Turkish vessel sparked an incident in the Black Sea last month by refusing to give way to a convoy of Russian ships.

The alleged incident took place on November 24, the company said, the same day Turkey shot down a Russian warplane on the Syrian border, leading to the biggest crisis in ties between the two countries since the end of the Cold War.

Egypt said Monday it still has no evidence to back up Moscow's analysis that a "terrorist" attack had downed a Russian passenger plane at the end of October in the Sinai.

The jihadist Islamic State group said it smuggled a bomb on board that blew up the Russian jet on October 31, killing all 224 people on board.

A Russian destroyer in the Aegean Sea on Sunday opened fire to avoid a collision with a Turkish fishing boat, the defense ministry said, as a bitter dispute over the shooting down of a Russian warplane raged on.

"The crew of the Russian patrol ship Smetlivy which was located 22 kilometers (13.7 miles) from the Greek island of Lemnos in the northern part of the Aegean Sea avoided collision with a Turkish seiner," the ministry said, adding that the crew had fired small arms to warn the boat.

Twenty-three psychiatric patients, most of them elderly, died when a fire ripped through their care facility in southern Russia Saturday night, in the latest tragedy to hit mental health hospitals in the country.

"The bodies of 23 people have been found during an on-site inspection," the Investigative Committee said in a statement on Sunday, adding that a further 23 people were hospitalized.

Turkish Foreign Minister Mevlut Cavusoglu on Friday said Ankara's patience with Moscow after the downing of a Russian warplane on the Syrian border was "not unlimited", urging Moscow to react calmly.

"We are calling on Russia, our major trade partner, for calm. But we also say that our patience is not unlimited," Cavusoglu told the private NTV television in an interview.