What is the mechanism that actually prevents entry of the ship into Venezuela? The article makes it sound like the shipping company halted delivery on advice fr

What is the mechanism that actually prevents entry of the ship into Venezuela? The article makes it sound like the shipping company halted delivery on advice from their insurer: "In a subsequent tweet, the Venezuelan senior official explained that the owner of the vessel carrying the merchandise of food was informed by the insurance company that it was prevented from moving that cargo to Venezuela."