Abstract: Since the Crimean crisis, the US has continuously tightened financial sanctions on Russia.In the short term, this doesn’ t appear to be working very effectively, but in the long run, it has indeed had an irreversible impact on the Russian economy. Though the US has repeatedly upgraded its sanction plans, four puzzles have long remained unsolved: appropriate sanctions have avoided a humanitarian crisis, but raised moral dilemmas; actual enforcement of sanctions is getting more and more difficult; EU cooperation with the US is vital, but the two regions more often than not play different tunes; and the frequent use of sanctions weakens US legitimacy and integrity,leading to a degradation of the sanction mechanism. Sanctions have continued to be implemented since President Trump took office, but with some new adjustments. Full text available here.