Two Navy sailors in Southern California were arrested and accused of providing military secrets and sensitive information to Chinese intelligence officers, according to a pair of federal indictments unsealed on Thursday.

Jinchao Wei, known as Patrick Wei, 22, was charged with spying for the Chinese under the Espionage Act. Mr. Wei serves aboard the Essex, an amphibious assault ship moored at Naval Base San Diego, which is the home of the Pacific Fleet. As a machinist’s mate, investigators said, he had clearance that gave him access to sensitive national security information.

The second sailor, Petty Officer Wenheng Zhao, 26, also known as Thomas, was charged with taking bribes in exchange for providing sensitive U.S. military information to a Chinese intelligence officer posing as an economic researcher. Mr. Zhao worked at the Naval Base Ventura County in Port Hueneme, which is home to several aircraft squadrons and the service’s naval construction battalions in the Pacific.

The charges appear to reflect the Chinese government’s deep interest in the Navy’s Pacific Fleet and other aspects of the American military’s operations in that region, part of a broader effort by China to steal American corporate and national security secrets. Already, the extent of Chinese spying, including cyberbreaches, has prompted top national security officials to sound the alarm. In testimony before Congress this year, the F.B.I. director, Christopher A. Wray warned, “There’s no country that presents a more significant threat to our innovation, our ideas our economic security, our national security than the Chinese government.”

In a news conference in San Diego on Thursday, Randy S. Grossman, U.S. attorney for the Southern District of California, said that Mr. Wei, 22, a naturalized ci