President Donald Trump may have just made Nord Stream 2 a household name. Ahead of a NATO meeting, the president blasted the German government on Wednesday for backing the new natural gas pipeline link from Russia to Germany. The president's point is that the United States is shouldering much of the budget for NATO, which was designed to counter the former Soviet Union and still acts as a bulwark against Russian aggression. In that light, Trump said Germany's support for the $11 billion Nord Stream 2 pipeline is "inappropriate." He took his complaint to his Twitter account on Wednesday. Tweet In launching the fresh attack against Germany, Trump waded into a long-running debate about energy security that has split the European Union. Here's a primer on the controversial Nord Stream 2 project.

What is Nord Stream 2?

Nord Stream 2 is a pipeline project slated to transport natural gas from eastern Russia to northern Germany, where it would link up with infrastructure that carries fuel to Western Europe. It would run 1,200 kilometers, mostly under the Baltic Sea along the existing Nord Stream pipeline — hence the name Nord Stream 2. The second line would double the system’s capacity to 110 billion cubic meters. Russian gas giant Gazprom is building Nord Stream 2. Five European companies, including Royal Dutch Shell and Wintershall, are shouldering half the cost of financing the project.

Why is Nord Stream 2 controversial?

Some European countries oppose Nord Stream 2, arguing that it increases Europe’s dependence on Russia and poses threats to their national security. The opposition comes primarily from the Baltic states and former Soviet satellite nations, including Ukraine, Poland, Estonia, Latvia and Lithuania. They argue Europe should not be filling Moscow’s coffers after Russia annexed Crimea in 2014 and in light of its broader efforts to destabilize the European Union. Nord Stream 2 also reduces Europe’s reliance on Russian gas that runs through Ukraine’s pipeline system, opponents say. That makes it easier for the Kremlin to punish its Eastern European neighbors by cutting off gas supplies while minimizing damage to its lucrative markets in the broader EU.

Where does the United States stand?

President Barack Obama opposed Nord Stream 2 and President George W. Bush came out against the original Nord Stream prior to its completion in 2011. Like the central and eastern European countries, they worried it increased Russian influence over the Continent. That policy has carried over into the Trump administration. Deputy Secretary of State John Sullivan summed up the U.S. position during a trip to Kiev earlier this year: We advocate for a strong, independent, self-sufficient energy future for Ukraine. One that is not dependent on Russia and subject to being an instrument of Russian aggression. We are against the Nord Stream 2 pipeline for that very reason, which would for the European continent undermine our goals of energy diversification and energy independence but at least as significantly it would undermine Ukraine. In May, U.S. Deputy Assistant Secretary of State for Energy Diplomacy Sandra Oudkirk told reporters the United States could sanction Nord Stream 2, using a law passed in 2017 that targets Russian energy projects around the world.

Does Germany need the supplies via Nord Stream?