Myanmar authorities have burned more than $600 million worth of seized illegal drugs, including heroin, methamphetamine, ketamine, marijuana and opium, in nationwide events marking the U.N.’s International Day Against Drug Abuse and Illicit Trafficking

YANGON, Myanmar — Thick clouds of black smoke billowed into the sky on the outskirts of Myanmar’s largest city Friday as authorities burned more than 50 tons of heroin, opium, ketamine, methamphetam…