The “Northern Triangle” of Central America—Honduras, Guatemala and El Salvador—is one of the world’s most dangerous regions. Drug trafficking and a weak rule of law have spawned powerful organized-crime networks that have overwhelmed government institutions. The instability has cost the region economically, feeding a vicious circle of poverty and violence with spillover effects for Mexico and the U.S.

The Trump administration recognizes that faster economic growth is part of what’s needed for the region and is looking beyond...