The European Union will discuss at an emergency meeting on Monday what steps could be taken if Russia halts gas supplies in retaliation to sanctions.

Several member nations view the decision by Western governments to impose penalties on Russia’s central bank and to exclude some of the country’s banks from the SWIFT messaging system as boosting the risk of retaliation, according to three EU diplomats with knowledge of the matter. 

President Vladimir Putin’s decision to invade Ukraine highlights the EU’s dependence on Russian natural gas, forcing a re-think of national energy policies across the bloc. At the gathering, the European Commission is due to present its analysis of the security of energy supply and simulations of preparedness for supply shocks. Then ministers will exchange views on current developments and potential emergency measures. 

Russia hasn’t indicated that it will halt supplies, though the war in Ukraine—a transit route for about a third Europe’s supplies of Russian gas—highlights the continent’s vulnerability to a disruption. Benchmark European gas prices surged by as much as 36% on Monday.

Russian gas exporter Gazprom PJSC has limited shipments to Europe in recent months, while stressing that its long-term contractual obligations were met. Germany’s economy ministry said on Monday that purchases of Russian gas are still possible using SWIFT messaging system even after sanctions.

The Russian attack on Ukraine has triggered calls from some politicians and companies for a ban on purchases from Gazprom. The Commission, the 27-nation bloc’s executive, has been urging a faster shift to clean energy under the Green Deal to reduce the reliance on imported fossil fuels. Its energy action plan due later this week is set to make the case for weaning the EU off Russian gas even stronger.

“Strengthening our energy sovereignty strengthens our security,” Robert Habeck, German vice chancellor and minister for economy and energy, said in a statement before the EU emergency gathering. “Therefore, we must first overcome the high dependence on Russian imports of fossil fuels—a warmonger is not a reliable partner.”

The Commission also asked energy ministers to pledge supplies of materials urgently needed by Ukraine, including diesel, petrol, jet fuel, coal, generators and power banks. There’s broad support among member states to provide assistance in the energy sector to the government in Kiev, said the three diplomats, who asked not to be identified.