(Bloomberg) -- Taiwan indicted 10 people including active-duty and retired military personnel on suspicion of spying for China, the latest case showing Beijing’s alleged efforts to infiltrate the island’s military.

Three of those indicted were said to have built a spy ring for China that recruited military personnel to collect state secrets, according to a statement from Taiwan High Prosecutors Office on Monday. 

Two active-duty soldiers were paid to film a video saying they would surrender to the People’s Liberation Army, for China to use as part of its psychological warfare, the statement said.

“Active-duty soldiers expressed their allegiance to the Chinese Communist Party, which is extremely vicious,” the statement said, adding prosecutors asked the court to impose harsh sentences.

Read more: Taiwan Holds Military Officers Suspected of Spying for China 

The US — Taiwan’s biggest military backer — has long been worried about the self-ruled island’s ability to keep tech and other secrets out of Beijing’s hands.  

Taiwan’s Defense Ministry warned last year that China’s spying posed a “serious threat.” Months later, Taiwanese officials detained three active-duty personnel and a retired Air Force officer on suspicion of spying. 

In July, Taiwan detained five more people over allegations they recruited officers to collect intelligence for China, which has pledged to bring Taiwan under its control someday — by force, if necessary. The following month, Taiwan launched an inquiry into several officers suspected of leaking military secrets to China.

During the investigation of the latest case, prosecutors asked to detain six of the 10 people, the statement said. One was later released on bail, while five remain in custody, according to a Central News Agency report, citing the office.

Taiwan’s Defense Ministry and national security unit were tipped off about the case and conducted joint investigations before reporting it to prosecutors, the Defense Ministry said in a statement Tuesday, adding that China’s intelligence-gathering efforts toward Taiwan were “all-pervasive.” 

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