The remote district of Rovieng was once a battleground between Cambodian government troops and Pol Pot‘s genocidal Khmer Rouge. Unexploded bombs still lurk in its fields and forests.

So does something more desirable – iron ore – and supposedly in such huge quantities two Chinese companies have an $11-billion plan to extract it. Their proposal – a steel plant and seaport linked by a 404-km (251-mile) railroad – has alarmed environmentalists, mystified mining and transport experts, and bolstered Cambodia’s reputation as an agent for Chinese expansionism in a region where the United States is increasingly competing for influence.