Associated Press
This image made from amateur video released by the Syrian Observatory for Human Rights and accessed Tuesday, Aug. 13, 2012, purports to show a Free Syrian Army soldier after firing a recoilless rifle during clashes with Syrian government forces at the village of Mukhtariya in the suburbs of Homs, Syria.

BERLIN — Economic sanctions have been called wars without bullets, yet their record in forcing political change has been mixed — by some estimates successful about a third of the time.

Nonetheless, sanctions have grown in popularity since the end of the Cold War as an alternative to armed conflict. They enable governments to take a stand without placing their soldiers in harm's way.

In Syria, where opposition activists say a 17-month uprising against President Bashar Assad has claimed more than 20,000 lives, Libya-style military intervention is not in the cards. So the United States and its Western allies have turned to economic sanctions as a way to promote political change.

As in shooting wars, however, events don't always go according to plan.

Sanctions sometimes backfire, deepening the suffering of ordinary people, prolonging a conflict by stiffening the resolve of autocratic governments or even triggering war, as when the U.S., Britain and the Netherlands imposed an oil and steel embargo against Japan in 1941.

In the most successful cases — such as sanctions in support of black majority rule in Africa or promoting democracy in communist Poland — it took years to achieve the goal.

An ongoing U.S. trade embargo against Cuba, slapped on the island nation after Fidel Castro nationalized American holdings, was imposed six months before President Barack Obama celebrated his first birthday. A half century later, Castro and his brother Raul are still in power.

A 2007 study by three scholars at the Peter G. Peterson Institute for International Economics found that sanctions were successful in undermining or changing a regime in only about 34 percent of the cases. Other studies argue even that figure is too high because the Peterson study included "successful" cases where military force was also used.