Iranian authorities are investigating a blaze that damaged seven ships at a southern Iranian port, the latest in a string of fires and explosions that have raised suspicions of coordinated sabotage targeting the nation’s infrastructure and a nuclear facility. Iranian state television showed black plumes of smoke billowing over the Bushehr port on Wednesday as firetrucks worked to extinguish the flames. A shipping-services provider operating at the port confirmed that at least seven vessels had caught fire. Authorities said…