Members of the European Union are at risk from a Russian gas supplier that views energy as a political tool, the European energy commissioner said Tuesday.

European markets get about 20 percent of their natural gas needs met by Russia, though most of that gas runs through the Soviet-era transit network in Ukraine. Simmering conflict, despite a recent cease-fire agreement, and ongoing debt rows between Kiev and Moscow expose a layer of vulnerability in the European economy.

EU Climate Action and Energy Commissioner Miguel Arias Cañete said energy diversity means energy security for member states.

"Without swift and decisive action, member states will remain dependent on a single supplier that views the sale of gas not simply as a commercial matter, but as a political weapon," he said in an address to policymakers in Brussels.

Contractual rows between Kiev and Moscow resulted in gas supply disruptions for Europe in 2006 and 2009. In response, member states have backed a series of alternative pipeline options covered under the banner of a string of projects dubbed the Southern Corridor.

Even then, Cañete said, member states will still be dependent on imports because of declining domestic production.

The steady drop in crude oil prices last year forced most major energy companies to cut spending on exploration and production in 2015.

Liquefied natural gas may be part of a comprehensive diversification strategy for Europe, Cañete said. That source may develop as a more viable option as bilateral trade negotiations with a gas-rich United States continue.

There are no free-trade agreements between the United States and potential European partners. Special concessions are needed to ship LNG to countries without such agreements.