Ukrainian airforce helicopter pilot Nadiya Savchenko on Tuesday blasted Russian prosecution 'lies' against her at the start of a trial over the murder of two journalists that has caused outrage in Kiev and the West. 

Savchenko faces up to 25 years in prison for her alleged role in the deaths of two Russian reporters killed by mortar fire last summer in eastern Ukraine.

Israeli Prime Minister Benjamin Netanyahu and Russian President Vladimir Putin have agreed on a plan to avoid "misunderstandings" in Syria amid an apparent military build-up by Moscow to support President Bashar Assad.

The two leaders reached an agreement on Monday during talks in Russia, with Israeli media reporting that the discussions involved avoiding clashes between the two militaries' jets over Syria.

Russia has deployed 28 combat planes in Syria, U.S. officials said Monday, confirming the latest move in Moscow's increasing military presence in the war-torn nation.

"There are 28 fighter and bomber aircraft" at an airfield in the western Syrian province of Latakia, one of the officials told AFP, speaking on condition of anonymity.

Russia is still sending weapons to separatist rebels battling the Ukrainian government despite a fresh truce in the war-torn east of the country, NATO chief Jens Stoltenberg said Monday.

"The ceasefire is mainly holding. This is, of course, encouraging because that was not the case before," Stoltenberg said on the first day of a visit to Ukraine. 

Russia's foreign ministry on Monday called for "concrete action" after a shell landed on its embassy compound in the Syrian capital, blaming forces battling Syrian President Bashar Assad.

"A shell fell on the territory of the Russian embassy in Damascus on September 20 around 9:00am, going deep into the ground without causing damage," the ministry said in a statement.

The U.S. embassy in Moscow on Monday ridiculed a Russian television channel after it posted a picture of the ambassador crudely photoshopped into an opposition rally.

The Ren TV channel claimed in headlines that U.S. Ambassador John Tefft "was sent to the opposition rally" held Sunday, posting a picture of him facing a media scrum with protesters in the background.

A Russian court on Monday sentenced a former military intelligence engineer to 14 years in jail for treason after he wrote to a Swedish organization seeking a job.

Gennady Kravtsov was accused of passing state secrets to Sweden by sending his resume in 2010. He was arrested on charges of treason in May 2014 as part of a classified case.

Israeli Prime Minister Benjamin Netanyahu met Russian leader Vladimir Putin in Moscow on Monday as Israel frets over a Russian military buildup in Syria.

Netanyahu was accompanied by his army and intelligence chiefs in a rare step for an overseas visit that Israel said would focus on Russia's maneuvering in the war-torn nation. 

Syrian Foreign Minister Walid Muallem predicted Sunday that Russia's increased involvement in his country would prove a game changer in the international campaign against the Islamic State jihadist group.

"More important than the supply of arms to Syria is Russia's participation in the fight against Daesh and al-Nusra Front," al-Qaida's franchise in the country, Muallem told Russia Today television, using an Arabic acronym for IS.

Hundreds of pro-Kiev activists from Crimea's Tatar community on Sunday launched a blockade of roads from Ukraine to the peninsula to protest Russia's seizure of their home region. 

Accompanied by members of the Ukrainian ultra-nationalist Pravy Sektor group, protesters from the Muslim Tatar community used concrete blocks to partially seal off the three roads linking mainland Ukraine to Crimea in an attempt to halt the delivery of goods.