Europe's dependence on Russia's energy and gas has made Brussels vulnerable to the Kremlin, so much so that in recent tensions between the two sides over Ukraine, NATO has publicly expressed concern about the European situation in the event of war or economic sanctions.

Iran PressEurope: The European Union depends on Russia for around a third of its gas supplies, and any interruption would exacerbate an existing energy crisis caused by a shortage.

Russia has massed some 120,000 troops near its neighbor and demanded the western defense alliance withdraw troops and weapons from eastern Europe and bar Ukraine from joining NATO.

Europe needs to diversify its energy supplies, the head of NATO said on Sunday, as Britain warned it was "highly likely" that Russia, the continent's biggest natural gas supplier, was looking to invade Ukraine.

US officials say Russia intends to invade Ukraine by strengthening its military buildup on the border with the country, but Moscow denies any plan to invade.

The United States, which has threatened Russia with significant new sanctions if it invades Ukraine, has said it is waiting to hear back from Moscow. It says NATO will not withdraw from eastern Europe or bar Ukraine from joining, but it is prepared to discuss topics such as arms control and confidence-building measures. 

"We are concerned about the energy situation in Europe because it demonstrates the vulnerability of being too dependent on one supplier of natural gas and that's the reason why NATO allies agree that we need to work and focus on diversification of supplies," NATO Secretary-General Jens Stoltenberg said.


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