ROME, Dec 22 (Reuters) - The European Union has little leverage with Russia over Ukraine, but needs to keep talking to Russian President Vladimir Putin to calm tensions, Prime Minister Mario Draghi said on Wednesday. Draghi told reporters that Europe did not have a major military force of its own and said he saw little prospect of using sanctions on Russian gas imports as a way of forcing Putin to back down in his confrontation with Ukraine. Russia has amassed tens of thousands of troops on its border with Ukraine leading to fears that Putin is planning an invasion of the country -- something Moscow has denied. "What deterrence can Europe deploy? This question should give us pause for thought," Draghi told reporters at an end-of-year news conference. "Do we have missiles, ships, cannons, armies? At the moment no," Draghi said, adding that NATO"s strategic focus was not on Russia but rather on the Indo-Pacific region -- an area embracing the Indian Ocean and the Pacific Ocean. "We Europeans have at most some sort of economic deterrence. But even here, we need to think a moment. If we want to impose sanctions that also include gas ... are we really capable of doing it in a strong enough fashion at the right moment? Clearly the answer is "no"," he said. Given these limitations, the European Union needed to maintain "a state of engagement" Putin, Draghi said, adding that he thought it was still possible to avoid "irreversible decisions" regarding Ukraine.