China expelled two former defense ministers from the ruling Communist Party over alleged corruption Thursday, the latest sign of a secretive crackdown sweeping the country’s elite.

The moves against Li Shangfu and his predecessor, Wei Fenghe, follow a series of shake-ups at the top of the world’s largest military — Li was ousted from the role last year after disappearing without explanation. The apparent purge comes as Beijing clashes with the United States over the fate of Taiwan, and as…