For decades, sanctions have been used as a diplomatic tool to pressure governments to change their bad behavior. VOA's Margaret Besheer takes a look at how sanctions are imposed and enforced.

When a country feels it is necessary to impose sanctions on another government, the head of state or the national legislature has the authority to impose punitive measures.

But Professor Tom Weiss of the City University of New York says unilateral sanctions are difficult to enforce.

"Rarely does a single country have enough leverage to make sanctions work because there are always alternative sources of supply," said Weiss. "And there are numerous ways for a country that is sanctioned to break the sanctions."

Since few countries have the influence necessary to enforce effective sanctions on their own, they usually go through the United Nations Security Council in the hopes of imposing comprehensive sanctions that have the broad support of member states.

U.N. Security Council

The Security Council has used its power to impose sanctions when international peace has been threatened and diplomatic efforts have failed. In the last few years, the trend has been toward targeted or so-called "smart" sanctions. They include economic and trade sanctions, arms embargoes, travel bans and financial measures, such as freezing assets.

Gary Hufbauer of the Peterson Institute for International Economics says smart sanctions are directed at regimes and tend to spare suffering within the general population.

"If you can somehow deprive the elite of their bank accounts, of their schools in Switzerland, their travels and so forth, at least you don't penalize ordinary people," said Hufbauer. "So the plus of that is that you don't have the bad side of sanctions, which is widespread ill-health or malnourishment, especially of older people and children, which causes a lot of backlash."

Just this month [March 2008], the Security Council used its mandate to impose targeted sanctions against the Iranian government for its controversial nuclear activities, which some nations believe is a cover for a secret nuclear weapons program. Professor Weiss says this latest round of sanctions against Iran is likely to only have a symbolic impact.

"The regime [in Iran] is clearly not keen to have these sanctions," he said. They clearly want to be a member of the international community of states and they spent a lot of diplomatic effort to make sure these sanctions did not come about. Not because it is going to have a real impact, in terms of day-to-day economics, but it is going to have a large, symbolic impact."

Once the Security Council imposes sanctions, such as the ones against Iran, there are several specialized U.N. agencies and other intergovernmental organizations that play a role in their monitoring, implementation and compliance.

One of the most important is Interpol -- the world's largest international police organization. More than 180 countries belong to Interpol, and the organization's highly trained personnel help enforce arms embargoes, travel bans and financial sanctions. International customs and aviation authorities are also key to enforcement.

Regional organizations such as the European Union, the Arab League and the Organization of American States have also played important roles in sanctions enforcement.

But despite international efforts to enforce sanctions, many experts say they cannot be used on their own and need to be part of a broader equation in order to be effective.