This latest incident is one a series that has raised tensions between the two countries verging on a trade war. Chinese food safety and import officials have instructed inspectors to increase checks on pistachio nuts imports following the discovery of a 20-tonne shipment from the US that was found to contain rotting nuts and an infestation of ants, the Xinhua news agency reported this week. The shipment, which has not entered into the supply chain will be destroyed, the agency said. China has itself been subject to intense criticism in recent weeks following a serious of health scares involving food, drugs and other products including poisoned cough syrup and pet food. This has prompted onlookers to question whether the motives are retaliatory or an attempt to protect the emerging domestic nut production market. Last week, Chinese inspectors destroyed or returned shipments of US nutritional supplement capsules and raisins after detecting unacceptable levels of bacteria. "Items that do not meet safety and health standards must be handled strictly according to the rules, and in serious cases the goods must all be either returned or destroyed," China's General Administration of Quality Supervision, Inspection and Quarantine said, according to Xinhua. The administration also have stated that special attention will be paid to shipments of US healthcare products, poultry and pork, seafood and processed food oils, Xinhua said.