The United States overwhelmingly leads the world in hosting child abuse Web sites, according to a new survey by the Internet Watch Foundation (IWF). The U.K.-based IWF claims over the last decade the U.S. is the source of 51 percent of sites featuring examples of child abuse, followed by Russia (20 percent), Spain (7 percent) and Japan (5 percent). Only 1.6 percent of the reported sites over the same period were traced to the U.K., a reflection of the different policies between the United States and the U.K. In the U.S., law enforcement officials tend to let child-abuse sites exist while conducting an investigation in hopes of not tipping off the site operators that an investigation is under way. The U.K., on the other hand, almost immediately issues a takedown notice when a site is discovered.