The international community has reacted swiftly to North Korea's latest nuclear weapons test. On Tuesday, the US and China submitted a draft proposal for tougher sanctions that would ban the delivery of luxury goods and make it more difficult for the leadership to move funds around the world. Last week, EU foreign ministers agreed to tighten sanctions against Pyongyang, banning the delivery of components used to build rockets. The 27-member bloc also planned further punitive measures against North Korea's financial sector.

The United Nations also imposed sanctions after Pyongyang's first atomic test in 2006 and subsequently tightened them in response to its second test in 2009. Yet North Korea seems unfazed by the international sanctions regime and continues to develop its nuclear program. And Michael Brzoska, head of the Institute for Peace Research and Security Policy at the University of Hamburg, is convinced that further tightening sanctions against Pyongyang will have "little impact" on the communist state's actions.

The case of North Korea shows that sanctions are not always effective. That's primarily because the international community often proves unable to forge a united front. China, for example, continues to supports its North Korean ally - despite the sanctions.

"That of course reduces the effectiveness of the sanctions," Christian von Soest, political scientist at the Leibniz Institute for Global and Regional Studies in Hamburg, told DW. "It demonstrates that sanctions are the most effective when they are coordinated among close partners and neighbors."

The same also applies to Iran. Tehran is suspected by the EU, Israel and the US of developing atomic weapons under the guise of a civil nuclear program. In order to prevent Iran from enriching uranium, the UN Security Council imposed sanctions against the Islamic Republic in 2005 and tightened them in 2007 and 2010. The EU and the US supported even tougher sanctions, but these were rejected by China and Russia.

Double-edged sword

The broader the international support for sanctions, the more effective they are likely to be. The UN condemned apartheid in South Africa as early as the 1950s. During the 1970s, international pressure increased. Many nations boycotted virtually every form of cultural exchange with South Africa or refused to let South African citizens into their country.

The South African economy suffered during the 1980s under trade sanctions imposed by Europe and the US. Historians still debate whether or not the sanctions ultimately led to the end of apartheid. For some researchers, the measures against South Africa are an example of the effectiveness of sanctions. But critics argue that the sanctions actually hurt the predominantly black population.

Sanctions can also strengthen the targeted regime. In authoritarian states that have no free media, the government can blame economic problems on sanctions and thereby strengthen its support among the population.

"It's called the Wagenburg mentality," said Christian von Soest. "That means that everyone comes together in the face of a common enemy. In this situation, you get exactly the opposite of what you actually want to achieve - resistance against the regime."

War-like consequences

Sanctions are the middle ground between rhetoric and military force. But the consequences for the population can be as catastrophic as war. Iraq faced UN sanctions from 1990-2003. According to UNICEF, infant mortality in Iraq increased by 160 percent from 1990-2000, 10 times as high as during the civil war in Rwanda. The Irish diplomat Denis Halliday once labeled the trade embargo against Iraq as genocide. But such drastic sanctions are rarely imposed these days.

"Today, there are targeted sanctions, which are directed at specific actors, such as the ruling elite," Christian von Soest said. "Bank accounts are frozen or travel bans imposed."

Yet even targeted sanctions can impact the civilian population. For example, Iran cannot import enough gasoline due to sanctions. The country has resorted to using self-made fuel of a lesser quality, which is polluting the Islamic Republic's big cities.