One-third of Europe’s gas comes from Russia and half of that flows through Ukraine. Here BBC tackles the sticky wicket.
Each escalation of the crisis in Ukraine sends a jolt of nervousness far beyond its borders as Europe worries about its energy supplies.
With about one-third of Europe’s gas coming from Russia and about half of that gas flowing through Ukraine, these are tense times.
Most worried are the four EU member states which get literally all of their gas from Russia – but another 12 rely on Russia for more than half their supply.
Conversations in recent days – mostly off-the-record – with pipeline operators, energy executives and government officials reveal a series of concerns.
And one phrase keeps coming up to describe what is at stake as energy emerges as a potential weapon: oil is money but gas is power.
If progressively tougher sanctions are imposed on Russia, would President Putin retaliate by closing off the gas taps? Or would that cost Russia too much?
If Ukraine continues to stall on settling gas bills which it regards as unfairly hiked, would Russia starve it of gas?
Talks in Warsaw on Friday between Ukraine, Russia and the EU will attempt to find a settlement.