FBI Director Christopher Wray has repeatedly warned the public that China poses by far the greatest espionage threat to the United States — perhaps the greatest such threat in our history given the vast scope of Beijing’s stealing American secrets of every kind, public and private.

The news on Thursday again proved as much.

The Department of Justice announced the arrest of two serving U.S. Navy sailors on suspicion of espionage for China. Both sailors are based in California. Both appear to be of Chinese descent or origin. This is the customary intelligence recruitment model employed by Beijing.

The first sailor taken into custody, 22-year-old Jinchao (Patrick) Wei, was arrested on Wednesday. Machinist Mate 3rd Class Wei joined the Navy in July 2021. He is assigned to the USS Essex, an amphibious assault ship homeported in San Diego. According to the Justice Department's statement , Wei held a security clearance (presumably at the "secret" level given his job), and in February 2022, he began communicating with a Chinese intelligence officer using clandestine methods. That Chinese spy tasked Wei with handing over a significant amount of sensitive Navy and Department of Defense information in exchange for several thousand dollars. The information Wei passed to Beijing included photos and videos including technical information about the Essex and other Navy ships, almost 60 technical manuals on the operation of Navy vessels, detailed systems manuals about Navy ships, and nonpublic information about Marine Corps exercises.

Wei knew this was wrong. Telling the tale, his Chinese spy handler ordered Wei not to discuss their clandestine relationship with anyone plus to destroy any evidence of his selling Pentagon secrets to Beijing. He is facing a long prison sentence if convicted. As the U.S. Attorney for the Southern District of California stated about Wei: "The crime of espionage under U.S. Code Section 794 has never been charged in this district, and until today had only been charged five times in the last six years across the entire country."

Then there's Construction Electrician 2nd Class Wenheng (Thomas) Zhao of Monterey Park, California. The 26-year-old Zhao enlisted in the Navy in April 2017 and is currently assigned to Naval Construction Group 1 — Seabees, in other words — at Port Hueneme, northwest of Los Angeles. According to the Justice Department, beginning in August 2021 and until at least May of this year, Zhao earned almost $15,000 by passing sensitive military information to a Chinese "economic researcher" seeking the information for "investment decisions" who was, in fact, an intelligence officer. Zhao sold information, photos, and videos regarding Navy exercise planning, maritime operations, ship movements, and logistical support, as well as photos of electrical diagrams and blueprints for a radar system stationed on a U.S. military base in Okinawa, Japan. Again, Zhao’s Chinese spy handler instructed him to conceal their relationship and destroy evidence of their business deals. Zhao is facing up to 20 years in prison for his alleged crimes.

Several things stand out here.

First, the FBI clearly had these suspects on their radar for some time prior to their arrests. The assumption that they were unmasked by good American counterintelligence work seems safe. That said, what Wei and Zhao are alleged to have passed to Beijing is serious stuff. While the sailors accepted money for their espionage, it seems likely that their Chinese ethnicity was a factor here. Beijing ruthlessly exploits overseas Chinese, particularly if they have any family in the old country, who are vulnerable to state pressure.

Here we must ask why the Pentagon keeps granting security clearances to Chinese Americans without special scrutiny. Unless such immigrants have completely cut their ties to their homeland, which happens but is rare, they are vulnerable to exploitation by Chinese intelligence. Prominent Democrats, including members of Congress , have assisted Beijing for years by asserting that U.S. counterintelligence is targeting Chinese Americans on grounds of "racial profiling." They are doing Beijing’s bidding while putting the cart before the horse: it’s China that’s racially profiling here by exploiting Chinese Americans to spy on their new country.

Until we get serious as a country about counterintelligence, which broadly we are not , Beijing will keep stealing our secrets. We bagged two bad guys this week, but how many more are out there, spying on the U.S. military from the inside? We should count ourselves lucky that Wei and Zhao lacked access to high-grade secrets, which they surely would have sold to Beijing.

We have yet to find the next John Walker, the notorious Navy warrant officer who for nearly two decades during the late Cold War compromised nearly all Navy communications to Moscow. If Walker’s successor is out there, selling such vital secrets to Beijing, the U.S. Navy may lose the looming Pacific War in its first week.

John R. Schindler served with the National Security Agency as a senior intelligence analyst and counterintelligence officer.