By Andrea Shalal, Andreas Rinke and Jeff Mason WASHINGTON (Reuters) -U.S. President Joe Biden said on Monday that the Nord Stream 2 gas pipeline would be halted if Russia invades Ukraine and stressed unity with German Chancellor Olaf Scholz as the West rallies to avert a war in Europe. At a White House press conference with the new German leader, Biden, a longtime opponent of the decade-old pipeline project https://www.reuters.com/article/ukraine-crisis-nordstream-idUKKBN2JY1SF to Germany from Russia, said Russian forces crossing into Ukraine would trigger a shutdown. “If Russia invades, that …