China has hit back at U.S. government's claims that most of the imports of fentanyl, the drug driving America's opioid crisis, are coming from China. China said it would not take the blame for the U.S. own fentanyl abuse problems. The Office of China National Narcotics Control Commission termed the U.S. accusation as baseless and irresponsible. The office said China had taken tougher measures to control fentanyl-related substances. From May 1 till now, not a single case of fentanyl trafficking from China to the United States has been identified.