Last month, the BBC reported that Pakistani peacekeepers in the Democratic Republic of the Congo had sold guns for gold. This followed well documented allegations in the same theater of sex for food with children.

Protection of civilians is now at the center of the United Nations' peace and security agenda. Its most visible global security footprint is the 18 peacekeeping missions around the world in which almost 90,000 soldiers, military observers, civilian police and international civilian staff are serving. The number of missions and the rising demand for U.N. peacekeepers is proof positive that their accomplishments are genuine and substantial. They do a lot of good, often under very challenging conditions. Even so, the real U.N. scandal over the past decade was not the oil-for-food program in Iraq, but the continuing abuse of civilians by U.N. peacekeepers. Preying on the people peacekeepers are meant to protect violates the core integrity of the missions and the United Nations.

With the typical tour of peacekeeping duty being six months, almost 200,000 personnel from more than 100 countries are rotated through the U.N. operations every year. One-third of civilians are new to the missions at any given time.

In such an environment, there is a constant need for vigilance and training on standards of conduct. Charges of sexual exploitation and abuse have been among the most publicized misdeeds by U.N. peacekeepers. But by no means are they the only side-effect of the large number of missions and very large number of personnel living and working in isolation, far away from home and family, in conditions of loneliness, and without the discipline of the behavior-regulating norms and codes of conduct of their home countries.

Any action can have unintended as well as intended consequences, and both beneficial and baleful outcomes. The empowerment, enrichment and emboldening of Iran, for example, is an undisputable but hardly an intended consequence of the Iraq war.

U.N. peace operations are designed to achieve myriad goals. The achievement of intended goals constitutes success for the operations. Nonachievement of the goals represents mission failures but does not constitute unintended consequences.

Conversely, not all unintended consequences are bad. A major consequence of the Indian Ocean tsunami was peace in Aceh. Soldiers from Bangladesh, India and Pakistan working together in U.N. missions around the world is another unintended but positive side-effect. Soldiers from some South American countries with a history of military rule are socialized into the precept and practice of civilian supremacy.

Most studies of peace operations have focused on the stated mandates and implicit goals, and the success or failure in implementing the mandates with skill and efficiency. This probably reflects the liberal bias informing the missions, that they are well-intentioned on the part of the United Nations and those contributing civilian, police and military personnel.

Yet peace operations can and do produce negative consequences that were never intended, such as an increase in corruption and inflation, an explosion of prostitution and sex trafficking, and an upsurge in underworld criminal activity, caused by the flood of international money. In East Timor, for example, given the size of the fledgling nation's economy, the presence of a sizable number of international personnel seriously distorted the economy, including the housing and hotel market. Often the presence of large numbers of people on international salaries creates a shadow economy that drains skills, experience and talent away from the national bureaucracy.

Another unintended consequence of peace operations has been the spread of HIV/AIDS. This is due to factors both in countries contributing troops and host nations. It is a lethal mix with no easy solution. In some of the war-affected countries of deployment in sub-Saharan Africa, the HIV prevalence rate is as high as 40-60 percent.

Soldiers tend to be mainly men of a sexually active age, with money in their pockets well in excess of prevailing per capita income levels, deployed away from home for months at a time and, by temperament and training, prone to risk-taking behavior. Often they come into contact with young boys and girls who are poor, unemployed and with a higher than normal rate of having been sexually exploited as casualties of armed conflict. One study showed about 45 percent of Dutch military personnel serving with the U.N. peacekeeping mission in Cambodia in the early 1990s had had sexual contact with prostitutes or other local women during a five-month tour of duty.

According to another study, troops from countries with high HIV/AIDS prevalence rates account for one-third of U.N. peacekeepers. Some African military forces have infection rates as much as five times that of the civilian population. Some countries like Ghana conduct compulsory testing before selecting soldiers for mission deployment. Others resist for reasons of social and cultural sensitivity; some simply lack adequate testing facilities.

The number and seriousness of side-effects of U.N. missions increased along with the growing numbers and complexity of the peace operations after the Cold War. Some, for example children being raped by soldiers, cause serious harm to individuals and communities that the peacekeepers are meant to protect, weaken the ability of the mission to fulfill its mandate, erode the United Nations' legitimacy as the organization deploying and managing the peace operations, and soften support for it in host and troop-contributing countries.

To improve the effectiveness and enhance the legitimacy of peace operations, we must understand how unintended consequences are generated and how they can be anticipated and mitigated.

It is not always easy to identify proper legal remedies. Many of the allegations are difficult to prove in a court of law. The United Nations has no power to try the offending soldiers, who are subject to the disciplinary authority of their own military. Usually, the alleged perpetrator has returned home while the victims and witnesses are from countries hosting the peace mission, often with weak criminal justice systems.

Yet somehow peacekeepers must be held internationally accountable for criminal acts. In addition to training in human rights standards and international humanitarian law, they must be brought within the jurisdiction of the International Criminal Court and be made subject to prosecution. Simply setting up new task forces and committees is not enough. Model actors are better than model codes; both require partnership and cooperation between the U.N. Security Council, Secretariat, Department of Peacekeeping Operations, the High Commissioner for Human Rights, and the ICC prosecutor. Countries that demur from the more stringent standards, codes of conduct and international investigations and prosecution should be excused from contributing personnel to U.N. operations.

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