Gazprom is cracking the whip in Kiev, requiring its delinquent customer to prepay its June gas bill by next Friday. This isn’t just a problem for Ukraine, though: Some 15 percent of Europe’s gas supply could be affected, if Ukraine can’t come up with the funds.

The Russian gas company Gazprom just announced a massive additional $11.4 billion charge for Ukraine. The charge comes under the controversial “take-or-pay” contract clause, and will put further strain on a state already struggling to stay afloat.

The massive unpaid gas bill that Ukraine owes to Russia is due today. Kiev’s new Prime Minister has publicly repudiated Gazprom’s recent 80 percent gas price increase, but Ukraine has precious little leverage in this fight.