LONDON (Reuters) – Russia’s Foreign Ministry protested to the U.S. ambassador in Moscow on Saturday over remarks by U.S. Senator Lindsey Graham advocating that President Vladimir Putin be assassinated. It said in a statement that failure to unambiguously condemn the remarks and take concrete measures “will have a further devastating effect on Russian-American relations”, already in tatters following Western sanctions against Russia over its invasion of Ukraine. U.S. Ambassador John Sullivan was summoned to the ministry to be told that Graham’s comment would be treated as a serious crime in Rus…