BRUSSELS, Jan 12 (Reuters) - Moscow"s behaviour towards Ukraine will play a crucial role in the fate of the Nord Stream 2 pipeline, meant to transport natural gas from Russia to Germany in the future, the United States said on Wednesday. "From our perspective, it"s very hard to see gas flowing through the pipeline or for it to become operational if Russia renews its aggression on Ukraine," U.S. Deputy Secretary of State Wendy Sherman told reporters in Brussels after a meeting of the NATO-Russia Council. The pipeline, which is not yet operational, undermines the energy security and the national security of a "significant part of the Euro-Atlantic community", she said.