Barack Obama does not like to back his diplomacy with military force. He believes there should be a clear sequence of engagement: diplomacy, sanctions, more diplomacy, perhaps more sanctions, and only after all peaceful alternatives are exhausted, the possibility of force. Even then, the administration is loath to entertain such hypotheticals.

This explains why economic sanctions are now the default instrument of American coercive statecraft for confronting challenges to the international order. When Russia invaded Crimea in February, Mr Obama turned to his “favourite non-combatant command” at the US Treasury Department to design targeted sanctions to increase the costs of Russian revanchism.

Financial warfare has become the weapon of choice against Iran’s Supreme Leader Ali Khamenei and Syria’s Bashar al-Assad, as these men threaten to unwind the nuclear non-proliferation regime and turn Syria into even more of a slaughterhouse.

Iran’s sanctions were particularly important to Mr Obama. An American-imposed economic minefield, which both US Congress and the administration deserve credit for developing, persuaded Tehran to engage in more serious nuclear negotiations, leading to an interim nuclear agreement reached in January in Geneva, and more nuclear talks in Vienna this past week.

Read the article in full at the Daily Telegraph.