MINNEAPOLIS -- President Obama Friday acknowledged that the investigation into the downing of Malaysian Airlines Flight MH 17 is just getting underway, but he aimed many of his remarks squarely at Russian President Vladimir Putin.

He said Putin's support for the separatists set the stage for the disaster, which claimed all 298 persons aboard.

"Time and again, Russia has refused to take the concrete steps necessary to de-escalate the situation," Obama told the White House press corps.

"Violence and conflict inevitably lead to unforeseen consequences."

Obama said the missile that took down the Boeing 777 was fired from an area in eastern Ukraine controlled by pro-Russian separatists. The same group has already claimed responsibility for downing three other aircraft, including a Ukrainian military transport.

The Ukrainian government asserts the rebels accidentally shot it down, using a Russian supplied surface-to-air missile. That has not been proven yet, but Obama said the separatists created the conditions that led to the tragedy.

"We know that they are heavily armed and they are trained, and that's not an accident. That is happening because of Russian support," the president said.

Russia's Interests

And while Putin has incurred displeasure from Obama and other leaders for his nation's involvement in Ukraine, and been urged to respect Ukraine's territorial integrity, he has a strong strategic interest there.

"It's not surprising that Russia would want unusual influence on its own borders," Ronald Krebs, a University of Minnesota political science professor and international affairs expert, told KARE.

He said all world powers want to keep the nations on their borders within their spheres of influence, and Russia is no different.

"The Russian interest in Ukraine -- in a Ukraine that is friendly to Russia, that is aligned with Russia -- is probably greater than our interest in Ukraine," Krebs remarked.

"Americans should ask themselves, what are their interests in Ukraine?"

Krebs said one of the fallacies in American politics is the expectation that the U.S. can control what's happening in Ukraine and other hot spots in the world. He said Americans shouldn't be isolationists, but need to have realistic expectations.

"The United States' greatest strength today, relative to other powers, is its military power. But just because we have that military hammer, let's not pretend that all the problems around the world are a nail that we should use it for."

Months of turmoil

Only Wednesday Obama and European leaders announced a new round of economic sanctions against Russia, targeting banking and energy assets, in response to Putin's support for the separatists in Ukraine and his decision to annex the Crimean Peninsula in March.

In February pro-western Ukrainians revolted against then-President Viktor Yanukovych when he decided to turn away from a plan to form a stronger alliance with the European Union, and sought to bolster ties with Russian instead.

The Ukrainian parliament ousted Yanukovych, sparking resistance from the pro-Russian population in the eastern and southern portions of the country. The separatists are attempting to undermine current President Petro Poroshenko's efforts to align with western Europe.

Obama Friday said stepped up economic sanctions are under consideration, but did not anticipate military action.