SCHWERIN, Germany — Between a tram stop and a kebab shop, the gray building in the northeastern German city of Schwerin looks innocuous enough — and so does its tenant, the Foundation for the Protection of the Climate and Environment.Instead, it served as a conduit for at least 165 million euros from the Kremlin-owned energy company Gazprom to build one of the world’s most contested gas pipelines: Nord Stream 2.“This is as crazy as it gets — that a German government authority is taking money from Gazprom to complete the pipeline Gazprom can’t complete because they are under U.S. sanctions,” said Constantin Zerger of DUH, a prominent German environmental watchdog.Mr. Schröder’s conservative successor, Angela Merkel, whose constituency was in Mecklenburg-West Pomerania, approved Nord Stream 2 after Russia’s 2014 invasion of Crimea, and defended it even after Moscow hacked the German Parliament, assassinated a Chechen rebel in central Berlin and poisoned the Russian dissident Alexei Navalny.“It is the most successful example.” Russia Day In October 2014, seven months after Russia illegally annexed Crimea, Mr. Sellering, then governor of Mecklenburg-West Pomerania, hosted the state’s first “Russia Day.” A networking bonanza sponsored by Gazprom and Nord Stream, it was held in the Hotel Neptun, still called the “Stasi hotel” for its reputation as a hub of the former East German secret police."