The U.S. Department of Transportation is suspending 26 flights by Chinese airlines next month in a dispute over Beijing’s strict policies when travelers test positive for COVID-19.

The retaliatory move follows the Chinese government’s decision to limit inbound flights by U.S. carriers including United Airlines Holdings Inc. and Delta Air Lines Inc. China’s actions are “adverse to the public interest” and warranted “additional proportionate remedial action by the Department,” the U.S. regulator said in an order dated Thursday.

The U.S. government cited China’s practice of suspending flights by airlines if too many passengers test positive for the coronavirus after arriving even though they must be free of the disease to board a flight.

The dispute is a clash between China’s zero-tolerance policies aimed at limiting the spread of disease and the U.S. government’s insistence that China has violated international treaties on flight access. The U.S. has taken similar actions before, such as in January when it suspended 44 flights scheduled by Chinese carriers.

The temporary flight ban targets service in Sept. planned by several Chinese airlines, including Air China Ltd., China Eastern Airlines Corp., China Southern Airlines Co. Ltd. and Xiamen Airlines Co. Ltd.

RESPONSE IN KIND

The U.S. action is in response to China’s suspension of 26 flights by U.S. carriers since February.

China’s embassy in Washington on Friday didn’t immediately respond to a request for comment. Delta also didn’t immediately respond to emails seeking comment. Representatives for United and American Airlines Group Inc. said their companies wouldn’t have a statement on the action.

The Civil Aviation Authority of China on Aug. 7 said if at least 4% of passengers on a flight test positive for COVID-19 after arrival, one flight by that airline will be suspended. If the number reaches 8%, two flights will be suspended, the CAAC said.

The policy eases previous standards that could suspend an airline’s flights for two weeks or limit passenger loads to 40%, according to the U.S. departmental order.

The DOT said it is not seeking to ratchet up tensions, but acted because it believed China’s actions violate a bilateral agreement governing flights between the two nations.

The CAAC policy places an “undue culpability on carriers” because the Chinese government clears each passenger and requires that they present a negative test for COVID-19, it said.