Embargoes are special in that they are used to control trade and political relationships between countries. Embargoes is a form of economic sanctions and typically involve a complete or partial ban on any economic, political, or military ties with a specific country or entity either for a set period of time or indefinitely. Embargoes can be implemented for various reasons such as a response to a hostile relationship, to pressure groups to progress in a negotiation, or to punish an act of genocide or terrorism. They are mostly put into effect by a United Nations mandate as a form of international pressure, but they can also be unilaterally imposed. Examples of nations that have had embargoes placed upon them are North Korea, Iran, Syria, Cuba and Russia. The impact of an embargo can be far-reaching and often has a negative impact on the country that it is placed upon. Trade restrictions may cause the cost of certain items to increase within the affected country, which can have a destructive effect on what is already a struggling economy. Embargoes can also be used to limit access to weapons and other items used in warfare; a country that is removed from much of the global exchange may be forced to create its own weapons or source them from less influential nations. This can increase the risk of violence and high tension in the region. The use of embargoes can be an effective tool for controlling the relationship between two countries and for punishing aggressors. However, it is important to understand that any economic action takes a toll on those it is imposed upon, making it a powerful and potentially destructive tool for international relations.