Russian President Vladimir Putin warned European energy security was at risk because of disputes over Ukraine's gas debts. Russian company Gazprom suspended a price discount for Kiev following the February upheaval and Ukraine could lose out on gas supplies if it doesn't settle its debt, Putin said.
State Department spokeswoman Marie Harf said the U.S. government was frustrated with Russia's use of natural gas as a weapon.
"We’ve said very clearly that Russia should not use this as a weapon and that, actually, Russia has a lot to lose if they try to do so," she said during her regular press briefing Wednesday.
Russia sends the bulk of its natural gas supplies for European consumers through the Soviet-era gas transit network in Ukraine.
Russian Prime Minister Dmitry Medvedev said he wasn't optimistic about what he said was a "very complex" economic situation in Russia.