The United States president has avoided issue of sending arms to Ukraine during joint news conference with Angela Merkel on how to counter Russian aggression.
Barack Obama has thrown his support in unison with the German diplomatic efforts to contain Russia in Ukraine, stating that military alternatives under consideration by the White House remain a symbolic and fraught with danger.
In a joint press conference with chancellor Angela Merkel aimed at strengthening western unity, the president simultaneously ignored any pressure from some in Washington to send arms to Ukraine, preferring instead to keep any future options for ratcheting US support vague.
"Russian aggression has only reinforced the unity of the United States and Germany and our allies and partners around the world," Obama said. "We continue to encourage a diplomatic resolution to this issue, and as diplomatic efforts continue this week, we are in absolute agreement that the 21st century cannot stand idle and simply allow the borders of Europe to be redrawn at the barrel of the gun.
Shortly after the meeting, the Republican chair of the House armed services committee announced the launch of a bill in Congress to arm Ukrainian soldiers that would probably be vetoed by the White House.
Asked if the U.S. and Germany were playing "good cop, bad cop", Obama stressed that his punitive options remained largely limited to increasing the economic cost of Russian actions rather than preventing it outright.
"Russia obviously has an extraordinarily powerful military and you know, given the length of the Russian border with Ukraine, given the history between Russia and Ukraine, expecting that if Russia is determined that Ukraine can fully rebuff a Russian army has always been unlikely," he said.
"But what we have said is that the international community, working together, can curtail the costs of violation and ratchet up the costs for the violation of the core principle of sovereignty and territorial integrity, and that's exactly what we've done."
Merkel also acknowledged that the success of her negotiations was far from assured - suggesting both leaders see little prospect of preventing Vladimir from continuing to support Ukrainian separatists if he is determined to ride out the economic costs of sanctions.