Russian Foreign Minister Sergei Lavrov said Friday Moscow was worried about the stability of Macedonia and the whole Balkans region after after recent deadly violence there.

"The latest events in Macedonia are very worrying... as well as terrorist tendencies emerging in the Balkans," Lavrov told reporters in the Serbian capital.

A senior aide to Ukrainian President Petro Poroshenko on Thursday accused Facebook of political bias, ahead of a question-and-answer session with co-founder Mark Zuckerberg

"There is pro-Russian influence and pressure on the Facebook office in Russia," said deputy head of the presidential administration Dmytro Shymkiv, who is negotiating with the global social network to solve the problem.

Ukrainian President Petro Poroshenko has appointed John McCain, a hawkish U.S. senator who has pressed Washington to send lethal weapons to war-torn Ukraine, as his advisor, his administration said.

Ukraine's pro-Western authorities are putting together an advisory council to help the ex-Soviet country conduct reforms and build global support for Ukraine.

The Baltic states will formally ask NATO to deploy several thousand troops as a deterrent to Russia, Lithuania said Thursday, but the alliance gave no assurance that the request would be accepted.

NATO Secretary General Jens Stoltenberg said at meeting of the alliance's foreign ministers in the Turkish city of Antalya that he was aware such a request was being made but emphasized it was too early to assess the demand.

NATO and the European Union on Thursday said they wanted to tighten cooperation in the face of "new threats" emanating from the assertive policies of Russia in the ex-USSR and violence to the south of the military alliance's borders.

EU foreign policy chief Federica Mogherini, attending a meeting of NATO foreign ministers in Turkey's southern resort of Antalya, said the two organisations were "different in nature" but facing similar challenges.

A clutch of rusty old naval boats bob about mournfully in the Black Sea off the harbor of Ukraine's southern city Odessa near an ageing missile boat.

"The only way to get those pieces of junk moving is to get some paddles and start rowing," an officer says derisively.

Investigators and lawyers said Wednesday that they have built war crimes cases against Syrian President Bashar Assad and key institutions of his regime with documents smuggled out of the country.

The Commission for International Justice and Accountability (CIJA) has already built three cases against the regime for crimes against humanity and is continuing to assemble evidence against others in the regime as well as in the opposition.

U.S. Secretary of State John Kerry on Wednesday warned Russia that now was a critical time to implement a fragile peace deal to end the fighting in Ukraine, after his talks with President Vladimir Putin raised hopes of a slackening in tensions.

Kerry said there was an "enormous moment of opportunity" to bring to an end over a year of fighting in eastern Ukraine between government forces and pro-Russia separatists which has dragged relations between Moscow and the West to a new post-Cold War low.

Russia vowed Tuesday it was ready to work with the United States on a host of burning issues but insisted it would not bow to "coercion," as President Vladimir Putin hosted top U.S. diplomat John Kerry. 

On the highest-level U.S. visit to Russia since the conflict in Ukraine erupted in late 2013, Putin met with Kerry at his summer residence in the Black Sea resort of Sochi.

Turkey on Tuesday said nothing can justify Russia's actions in Ukraine and other ex-Soviet states, in a rare strong criticism of its increasingly close ally ahead of a NATO meeting.

Turkish Foreign Minister Mevlut Cavusoglu, whose country is a key member of NATO, said Ankara was prepared to play a "constructive role" in the disputes between Russia and the West over Ukraine.