The General Accountability Office of the federal government (GAO.gov), has carried out many studies on the effects of U.S. sanctions on Iran. The GAO has been skeptical of their utility. Here are excerpts from two reports, one from 2007 and one from 1992. The first report suggests that without strong internal opposition, sanctions tend to be ineffective. Of course, there is no organized internal opposition in Iran.
The GAO Has Doubts
Posted December 2007 at https://www.gao.gov/assets/280/270563.pdf
The effectiveness of sanctions is not primarily determined by the economic damage they inflict. Sanctions work best when there is strong internal political opposition to the target government, particularly internationally oriented commercial interests that want to retain business ties with the country imposing the sanctions. Where significant political opposition exists, imposing selected sanctions with the threat of more severe measures to follow often causes the opposition to pressure the target nation’s government to acceed to the sanctioning nation’s wishes. The success of the sanctions thus is more closely related to the threatened damage of subsequent measures than it is to the economic damage of sanctions actually in place. In the case of multilateral sanctions against South Africa, for example, measures of moderate economic effect raised fears of future sanctions among more liberal white businessmen opposed to the policy of apartheid. Their lobbying for change helped create pressure for the reforms instituted in South Africa.
Even with significant internal political opposition (and even more so without it), imposing harsh, comprehensive sanctions immediately may be counterproductive. The target government may use the severe economic pain to rally its population in the face of an external enemy. In the early to mid-1960s, Fidel Castro used the harsh effects of the comprehensive U.S. embargo to win additional popular support in Cuba.
Posted February 19, 1992 at https://www.gao.gov/assets/160/151591.pdf
Impact in Furthering U.S. Objectives Is Unclear and Should Be Reviewed: What GAO Found
Since 1987, U.S. agencies have implemented numerous sanctions against Iran. First, Treasury oversees a ban on U.S. trade and investment with Iran and filed over 94 civil penalty cases between 2003 and 2007 against companies violating the prohibition. This ban may be circumvented by shipping U.S. goods to Iran through other countries. Second, State administers laws that sanction foreign parties engaging in proliferation or terrorism-related activities with Iran. Under one law, State has imposed sanctions in 111 instances against Chinese, North Korean, Syrian, and Russian entities. Third, Treasury or State can use financial sanctions to freeze the assets of targeted parties and reduce their access to the U.S. financial system.
U.S. officials report that U.S. sanctions have slowed foreign investment in Iran’s petroleum sector, denied parties involved in Iran’s proliferation and terrorism activities access to the U.S. financial system, and provided a clear statement of U.S. concerns to the rest of the world. However, other evidence raises questions about the extent of reported impacts. Since 2003, the Iranian government has signed contracts reported at about $20 billion with foreign firms to develop its energy resources. Further, sanctioned Iranian banks may fund their activities in currencies other than the dollar. Moreover, while Iran halted its nuclear weapons program in 2003, according to the November 2007 National Intelligence Estimate, it continues to enrich uranium, acquire advanced weapons technology, and support terrorism. Finally, U.S. agencies do not systematically collect or analyze data demonstrating the overall impact and results of their sanctioning and enforcement actions.
Iran’s global trade ties and leading role in energy production make it difficult for the United States to isolate Iran and pressure it to reduce proliferation and support for terrorism. For example, Iran’s overall trade with the world has grown since the U.S. imposed sanctions, although this trade has fluctuated. Imports rose sharply following the Iran-Iraq war in 1988 and then declined until 1995; most export growth followed the rise in oil prices beginning in 2002 (see figure). This trade included imports of weapons and nuclear technology. However, multilateral UN sanctions began in December 2006.