The Chinese spy machine infiltrating Taiwan’s military

As a member of the military police battalion tasked with guarding the offices of the president and many senior officials, he knew the security personnel and measures used to protect them.

He was also in debt and short on cash. So when he searched online for a loan to keep himself afloat, a Chinese agent hooked him with an opportunity for easy money. All the sergeant had to do was snap some photos of sensitive security details with his cellphone.

Lai, according to Taiwan authorities, was a cog in an extensive Chinese spy machine that has infiltrated Taiwan’s armed forces and political establishment, funneling intelligence to Beijing.

As China’s adversaries around the world labor to shut the door on Beijing’s espionage operations, nowhere is the threat of infiltration greater. Taiwan officials fear that agents already in place on the island would aid a military attack by China, which claims Taiwan as its own and has threatened to seize it by force.

China’s spying operations are rapidly advancing, using complex operations and new technology that together pose “a potential serious threat to our national security," Taiwan authorities said in a recent assessment.

A campaign launched in March by Taiwan President Lai Ching-te to combat Chinese espionage and influence has yielded some high-profile arrests that shed new light on China’s strategy to undermine the island from within.

Particularly unsettling for Taiwan: Many of the suspects charged with national-security violations since the start of 2024 were actively serving in the military or were army veterans.

In October, a retired lieutenant general was given a 7½-year prison sentence for accepting Chinese funds to establish an armed organization in Taiwan that would target military bases.

Taiwanese military investigators, law-enforcement authorities and prosecutors interviewed for this article described a trend in China’s effort: the increasing use of messaging apps and online loan offers to target low-ranking members of Taiwan’s armed forces.

In one example cited by a military officer, a Facebook post claiming to represent a podcast offered the equivalent of up to around $125 to any interview subject with a military background willing to share information.

“China has been taking advantage of democratic Taiwan’s freedom, diversity and openness to recruit gangs, the media, commentators, political parties and even active-duty and retired members of the armed forces and police to carry out actions to divide, destroy and subvert us from within," Taiwan’s president said in March.

Paying lower-ranking soldiers small amounts for their cooperation is “good value for the money," said David Hsu, the deputy head of Taiwan’s investigation bureau.

Posters displayed at military campuses around Taiwan warn soldiers to be wary. Chinese agents, they say, will charm you through social media, offer money and business opportunities and even provide sexual favors.

The posters feature illustrations and descriptions of the people who are particularly vulnerable: “Those who lead indulgent lifestyles off-duty, frequent inappropriate venues, gamble, or are preoccupied with online dating and extramarital affairs." Hotline numbers are provided to report suspicious activity.

Beijing is “not just benignly collecting information. It’s all being used in preparation for annexing Taiwan," said Kerry Gershaneck, a former U.S. counterintelligence official and author of a book on combating China’s “political warfare."

Hearts and minds

China is also trying to undermine Taipei with messages to the Taiwanese public that the island’s leadership is corrupt and its military unwilling to defend them.

In one example, prosecutors charged a Marine sergeant this month with undermining national security by allegedly recording a video of himself pledging allegiance to the Beijing government while holding a Chinese flag—and getting paid by someone in China over $6,000 for doing it. He earned a few hundred dollars more by providing information about Taiwan’s weapons and amphibious vehicles, prosecutors said. No legal representative for the accused could be reached.

Such “cases subtly undermine the trust that the Taiwanese can have in themselves" and “the trust of the allies and partners of Taiwan," said Peter Mattis, a former Central Intelligence Agency analyst who is president of the Washington-based Jamestown Foundation.

“It’s less of an intelligence war and more like cognitive warfare," Taiwan Defense Minister Wellington Koo said in a May interview.

China’s Taiwan Affairs Office didn’t respond to a request for comment.

Prosecutors in Taiwan filed charges in 2024 against 64 people in 15 cases of alleged Chinese espionage, compared with three in 2021, according to Taiwan’s National Security Bureau. In the first nine months of last year, 24 more were charged.

Nearly two-thirds of the people charged during those periods were military personnel, active or retired. Nearly 90% of the military cases came from internal tips, Koo said Monday.

One challenge for Taiwan is new spy tech—what government watchdog the Control Yuan has described as “China’s rapid advancements in defense and intelligence technologies."

In one example, an air-force sergeant used a Chinese-developed phone app to bypass military security software and photograph classified documents, according to Control Yuan officials.

In another, a Taiwan businessman used mapping technology to survey roads, documenting buildings, distances and other data that investigators said could be used to support Chinese wargames or military planning.

Sophisticated tools aren’t always necessary. Smartphones, with their built-in cameras, have made spying easier and stopping it more complicated, investigators and military officers said.

Spying at the presidential offices

Sgt. Lai’s battalion was responsible for security at the entrances and throughout the hallways of the presidential office building. The sprawling Taipei landmark also houses the offices of the vice president, the National Security Council and its chief, and other officials.

In April 2022, when former President Tsai Ing-wen was in office—and identifying the island as a democracy distinct from China, a position that infuriated Beijing—Lai began delivering photographs of documents to Chinese agents in return for payment in the cryptocurrency Tether.

Lai later brought a member of the Taiwan Defense Ministry’s cybersecurity and electronic-warfare command into his spying activities.

When Lai was eventually rotated out of the presidential-offices detail and risked losing access to lucrative intelligence, he recruited another sergeant and a corporal in his battalion to take over.

The more sensitive the files, the more they were paid.

Over the course of two years, the unit provided China with names and headshots of government officials who worked in the building, rosters of guards and their call signs, and the training materials that guided how they performed their jobs, according to court documents.

Such information could be assembled by China “to complete a big puzzle," said Lin Ying-yu, a security expert who teaches at Taiwan’s Tamkang University.

The operation continued through the January 2024 election of President Lai, who has deepened the divide with Beijing, labeling China a “foreign adversary."

In August 2024, a soldier tipped off authorities about the spying enterprise at the presidential office building. Sgt. Lai and three others were arrested that December. By March, they had been convicted. Lai was sentenced to seven years in prison.

Over the course of Lai’s spying enterprise, prosecutors estimate that he received the equivalent of about $15,000. The other three received similar pay.

“Sometimes it baffles us," said chief prosecutor Hsing Tai-chao. “It wasn’t even a significant amount."

Write to Joyu Wang at joyu.wang@wsj.com