While no link has been established implicating Russia in the firing of a missile that downed MH17 last week, the U.S., on Thursday, said there is evidence of Russian troops pulling the trigger and firing across the border at the Ukrainian military. "For several days the Russians have been firing artillery into Ukraine," a Pentagon spokesman told the Wall Street Journal. Russia has repeatedly denied involvement with the separatists fighting the government in eastern Ukraine, but a State Department spokeswoman said there is new evidence that Russia is planning to supply heavier and more powerful rocket launchers across the border to pro-Russia rebels.
Here’s more from the Journal:
Although used mainly to harass Ukrainian forces, U.S. officials remain worried that a sustained artillery barrage by Russian forces eventually could counter recent Ukrainian advances… U.S. officials say the escalation by Russia is a risk and represents a sign that Moscow is worried about the Ukrainian government's counteroffensive against the separatists. Moscow, U.S. officials say, is worried that if the separatists don't turn back the Ukrainian government's advances, the separatist cause could be severely damaged or even lost. Russia has between 15,000 and 18,000 troops on the Ukrainian border, but officials said there hasn't been a significant buildup of firepower since the downing of the Malaysia Airlines jetliner. Russian motorized infantry units all have artillery and rocket launchers assigned to them. The strikes, officials said, are a sign that Russian President Vladimir Putin isn't going to back down in his support for the separatists, even in the wake of the shootdown of the Malaysian airliner.
“The United States learned about the artillery fire through ‘technical and overhead’ intelligence systems,” a U.S. official told the Associated Press, “an apparent reference to spy satellites and signals-intelligence collection.”