For 3-4 days after the Malaysian Airlines crash the White House gave Russia an opening to de-escalate the crisis. At first Russia was quiet and then grew defiant.
The US has heard the message loud and clear. It signals that Russia is committed to the conflict and has no appetite to marginalize the rebels. In response the US ramped up sanctions last week and will add more this week.
The White House is correct when it says Russia is now ‘doubling down’ and the tragedy has proven to Obama that diplomacy won’t work. I think we’re on the cusp on an escalation from all sides.