Russian troops 'intervening directly' in Ukraine fighting: US ambassador

The United States accused Russia Aug. 28 of being directly involved in the Ukraine conflict after pro-Kremlin rebels seized swathes of territory from government forces in a new southeastern front.
      
"An increasing number of Russian troops are intervening directly in fighting on Ukrainian territory," the US ambassador to Kyiv Geoffrey Pyatt wrote on Twitter.
      
"Russia has also sent its newest air defence systems including the SA-22 into eastern Ukraine and is now directly involved in the fighting," he said.         

After weeks of government offensives that have seen troops push deep into the last rebel bastions in the industrial east of Ukraine, the tide has turned dramatically in the four-month conflict.        

Kyiv called on NATO for help after a rebel counter-offensive from the southeast border with Russia appeared to smash through an army blockade around the separatist stronghold of  Donetsk and threaten the government-held port city of Mariupol.
      
Ukraine's Prime Minister Arseniy Yatsenyuk blasted Russian President Vladimir Putin for having "deliberately unleashed a war in Europe" and called for an emergency UN Security Council meeting, a called echoed by Lithuania.
                      
A top rebel leader, Alexander Zakharchenko, on Wednesday admitted Russian troops were fighting alongside his insurgents, but said they were on "holiday" after volunteering to join the battle.
      
There has been increasing concern in Kiev and the West of Russia's direct involvement in the conflict -- a charge Moscow has repeatedly denied.
      
The spiralling tensions come after Ukrainian president Petro Poroshenko and Putin on...