https://www.zerohedge.com/news/2018-05-17/trump-gives-merkel-ultimatum-drop-russian-gas-pipeline-or-trade-war-begins

It became clear just how important it is to the US for Russia's Nord Stream 2 gas pipeline project to fail two months ago when, as we described in "US Threatens Sanctions For European Firms Participating In Russian Gas Pipeline Project", the U.S. State Department warned European corporations that they will likely face penalties and sanctions if they participate in the construction of Russia's Nord Stream 2 on the grounds that "the project undermines energy security in Europe", when in reality Russia has for decades been a quasi-monopolist on European energy supplies and thus has unprecedented leverage over European politics, at least behind the scenes.