China has hit back against a round of US sanctions with a barrage of counter-sanctions targeting a group of American companies and a tightening of export restrictions on the drone supply chain, the Ministry of Commerce announced on Wednesday.The export controls will subject any shipments of “drones, their key components and related technologies” to the US to “strict case-by-case scrutiny”, with the measures set to take effect immediately, the ministry said in a statement, citing the need to “safeguard national security and meet China’s international commitments on non-proliferation”.On the same day, the commerce ministry also added six US entities to its countermeasures list – banning Chinese entities and individuals from trading and cooperating with them – over allegations that they had assisted and supported US sanctions related to China’s western Xinjiang region, describing their conduct as “egregious”.A seventh US company, Compliance Testing LLC, was added to China’s countermeasures list for assisting the US Federal Communications Commission (FCC) in introducing measures that “endanger China’s sovereignty”.Separately, the commerce ministry on Wednesday also launched a national security investigation regarding imported printing and copying office equipment.The measures are a response to a string of recent actions by the US authorities.