Everybody wants to say he’s going to feed us horse (whatever, just label it properly), but the answer is probably much simpler: He got a bribe from Argentina to allow beef into the US that China rejected.
China rejects Argentine beef due to chloramphenicol: investigation and internal consumption crisis - Noticias Ambientales
On March 19, the General Administration of Customs of China suspended a shipment of 22 tons of beef from the slaughterhouse ArreBeef in Pérez Millán