A United Nations conference last weekend approved a historic agreement to fight global trafficking in small arms. Despite years of preparation, agreement hinged on last-minute negotiations, largely to meet U.S. objections. Fortunately, delegates understood the magnitude of the problem and put progress ahead of principle. An intermediate step has been taken to help rid the world of the scourge of small arms. Now governments must back the U.N. plan with action; enforcement of its terms will determine its success or failure.

In simplest terms, a small arm is a weapon that can be fired, maintained and transported by a single person. Also included in this category are light weapons, which can be carried by a pack animal or small vehicle. In other words, the terms cover all weapons from pistols to shoulder-fired antiaircraft missiles. It is estimated that there are 500 million such weapons around the world -- one for every 12th resident of the planet -- and they have become the weapons of choice because they are cheap and easy to use. Small arms were used in 46 of the 49 armed conflicts that were fought during the 1990s. Between 40 and 60 percent of these weapons are obtained illegally; the business is worth around $1 billion each year.

Since 1990, those weapons have claimed more than 4 million lives, the overwhelming majority of the victims - some 80 percent - are women and children. Millions more have been wounded, and over 14 million people have been uprooted in these conflicts. They have been forced to become refugees, and a potential source of instability in the countries to which they seek shelter. The use of small arms allows children to become soldiers; the psychological and social damage done by exposing children to war is incalculable.