Exporters of meat and other food to China are being required to certify that their products come from facilities that follow anti-pandemic safety standards.

Some exporters have signed statements to that effect, but the requirement is getting some pushback. The U.S. and others are criticizing it as unscientific and a roadblock to trade.

“Efforts by some countries to restrict global food exports related to COVID-19 transmission are not consistent with the known science of transmission,” U.S. Agriculture Secretary Sonny Perdue and FDA Commissioner Stephen Hahn said in a joint statement.

Bloomberg reports that the effort by China appears to be a way to reassure Chinese consumers, not a conscious effort to restrict trade.

Tyson Foods is the only major American food company to sign the Chinese statement, according to Bloomberg. China banned shipments from a particular Tyson plant in Arkansas after a COVID outbreak there.

Other American companies apparently worry that signing the Chinese declaration, which asks exporters “to ensure that food imported into China is not contaminated with the COVID-19 virus,” would expose them to liability.