New Delhi, Sept. 17 -- The day I reached Monrovia in 2004 to be part of the United Nations peacekeeping mission in Liberia, a nation ravaged by 14 years of civil war that killed a quarter million people and displaced twice as many, I was struck by an unexpected sight. On a muddy patch of land, logs served as goalposts for an improvised football ground. A match was underway. On one side was a team drawn from the UN mission. Their opponents? A squad of 11, consisting of freshly disarmed combatants from the country's civil war, some of them perpetrators of atrocities, others victims of the same.

Soccer-mad Liberians in their hundreds, mostly ex-combatants, were wildly cheering for their team, which eventually routed the UN squad 2-0.

It wa...