NATO on Wednesday defended the number of military exercises it has staged as a response to "growing Russian aggression" and refuted suggestions that they were helping make war in Europe more likely.

The alliance was reacting to a warning from a London-based think tank about the risks from a sharp increase in Russian and NATO war games since the conflict between the Ukrainian government and pro-Russian separatists flared up in April last year.

Syrian opposition figures head to Moscow this week although they are unlikely to welcome Russia's plan for a new anti-jihadist coalition that would include embattled Syrian President Bashar Assad.

Moscow has since June been pushing a plan for a broader grouping than the U.S.-led coalition fighting the Islamic State (IS) group, to include Syria's government and its allies.

A Russian soldier accused of killing a family of seven in Armenia, including two children, went on trial for desertion Wednesday at a Russian army base in the former Soviet state.

Conscript soldier Valery Permyakov is accused of murdering a man and a woman and their grown-up son and daughter, daughter-in-law and two grandchildren at their home close to the Russian base in Gyumri, some 55 miles (89 kilometers) from the capital Yerevan.

President Barack Obama's administration vowed to press ahead with a half-billion-dollar mission to train Syrian opposition fighters Tuesday, despite fears that its initial failures have dented U.S. credibility. 

After the routing of a 54-strong U.S.-trained force by al-Qaida allied rebels, Pentagon spokeswoman Commander Elissa Smith told Agence France Presse there was no plan to pause or scale back the program.

U.S. Secretary of State John Kerry accused China and Russia of "very likely" reading his emails Tuesday, adding that the U.S. has and will continue to discuss cyber attacks with China.

"The answer is it is very likely. It is not ... outside the realm of possibility, and we know that they have attacked a number of American interests over the course of the last days," Kerry said on the TV show CBS Evening News.

Georgia on Tuesday accused Russia of cutting off its citizens from their farmland by installing border signposts demarcating the breakaway South Ossetia region, calling on Moscow to refrain from "escalation."

The signposts have been installed near three villages in recent days and land belonging to several local residents ended up beyond the demarcation line with South Ossetia, a Georgian region that declared independence and which Tbilisi considers occupied by Russia.

The leader of a Caucasus Islamist group in Russia's restive Dagestan region has been killed in a mountain raid that included air strikes, Russian security services and Islamists said Tuesday.

Four people died in the operation by Russia's special forces and military, Dagestan's interior ministry said.

Investigators probing the shooting down of Malaysia Airlines flight MH17 said Tuesday they had identified possible Russian-made BUK missile fragments from eastern Ukraine, where the plane crashed.

International and Dutch investigators are probing "several parts, possibly originating from a BUK surface-air-missile system," said a joint statement from prosecutors and the Dutch Safety Board (OVV).

Saudi Arabia's foreign minister on Tuesday poured cold water on Russian calls to join forces with the Syrian authorities against Islamic State jihadists, insisting it would never work with President Bashar Assad. 

Moscow -- one of Assad's few remaining allies -- has called for coordination between the Syrian government and members of an international coalition fighting the extremist group, which controls swathes of territory in Syria and Iraq.

Ukraine vowed Tuesday to use all weapons at its disposal to withstand an alleged new pro-Russian rebel advance that added urgency to a goodwill visit by Britain's defense secretary.

Kiev accused the eastern separatist fighters of launching another missile assault north of Mariupol -- a government-held port that provides a land bridge between rebel territories and the Russian-occupied Crimea peninsula.