As the death toll in Syria approached 1,000, President Barack Obama finally announced sanctions against the regime. His move stopped Americans doing business with President Bashar al-Assad, along with certain relatives and officials, and froze their US assets. Cynics scoffed, repeating the conventional wisdom that sanctions don’t work. In fact they can make a big difference and, with Syrian violence worsening, the time is right for more.

Sanctions’ sceptics trot out a familiar litany, from the failure of a trade embargo to topple Fidel Castro in Cuba to the failure of sanctions to remove Saddam Hussein in Iraq. But evidence suggests such measures can be effective. A careful study by the Peterson Institute of 115 uses of economic sanctions by major countries between 1950 and 1990 concluded that, in about a third of cases, they helped those wielding them achieve their goals. The research shows they were most likely to be successful when this objective was modest and clear, the target was in a weakened position, economic links were significant, sanctions were heavy, and the duration was limited – conditions which partly apply in Syria today.

Even such positive statistics miss the more important question, namely what the alternative might be. The probability of success via sanctions may be relatively low – as is probably the case in Syria – but the relevant issue is whether it is higher than any alternative. Military power is sometimes effective, but its costs are also often high too, particularly in regions such as the Middle East.