By Jarrett Renshaw and Daphne Psaledakis BRUSSELS/WASHINGTON (Reuters) -The United States and its allies on Thursday imposed fresh sanctions on Russia, targeting dozens of Russian defense companies, hundreds of members of its parliament and the chief executive of the country’s largest bank as Washington ramps up pressure on Moscow over its invasion of Ukraine. The U.S. Treasury Department also issued guidance on its website warning that gold-related transactions involving Russia may be sanctionable by U.S. authorities, a move aimed at stopping Russia from evading existing sanctions. “Our purpo…