These sanctions have cut off Syria from U.S. economic aid and limited trade between the two countries, such as deterring American companies from investing in Syria and American banks from opening branches there. Because most U.S. exports are banned, the Syrian national airline has had trouble repairing its Boeing jets or buying certain European jets that include American content.

But there is little evidence that this long list has made much difference in curbing either the brutal nature of Syria’s government or in ending its tolerance of anti-Israeli militia groups that operate out of Damascus. Indeed, Syria embarked on a secret effort with North Korea to build a nuclear plant that was destroyed in 2007 by Israeli jets.