MAPUTO, Mozambique — When blowing up land mines for military training is accompanied by a goat sacrifice, the cultural divide between the U.S. and the rest of the world looms large. Yet more and more the job of U.S. troops abroad is to bridge that gap in the service of peacekeeping by training local armies.

As recent developments in Libya have shown, in some parts of the world the U.S. is loath to put its own troops into action, and having soldiers trained by the U.S. in countries near conflict areas like Somalia is an ever-more-appealing alternative. The future of Iraq depends in part on...