With new elections in October, Poroshenko will not want to look as though he is being soft on the rebels in the east, a criticism leveled at his predecessor Olexander Turchynov, or giving in to Russian influence. This will make the chances of conciliation even slimmer.
Read MoreUkraine may have an energy problem besides nat gas
With its recent memories of Soviet Union influence, Poland has been the most outspoken European country against Russia's actions toward Ukraine. This continued Thursday, with Foreign Minister Radoslaw Sikorski calling for "actions" against Russian "aggression."
The need for Russia's abundant natural gas supplies in Germany in particular has tempered the response to the crisis so far.
One of the ways Ukraine can put pressure on Russia's economy, and on European leaders to act, could be to refuse to transit Russian gas to Europe.