An investigation by The Associated Press and the PBS series “Frontline” has documented a sophisticated Russian-run smuggling operation that has used falsified manifests and seaborne subterfuge to steal Ukrainian grain worth at least $530 million. The AP and “Frontline” used satellite imagery and marine radio transponder data to track three dozen ships making more than 50 voyages carrying grain from Russian-occupied areas of Ukraine to ports in the Middle East. The ongoing theft is being carried out by wealthy businessmen and state-owned companies in Russia and Syria. Some of them already face financial sanctions from the United States and European Union. Legal experts say the theft is a potential war crime.