In an extremely concerning sign of increasing threats from China, there’s been a reported surge in gate crashing by Chinese nationals.

The Wall Street Journal reported Monday that Chinese nationals have gained access to military bases or other “sensitive sites” in what U.S. officials described as a “potential espionage threat.”

Multiple government agencies, including the FBI and Department of Defense have acknowledged that the so called “gate-crashers” have infiltrated U.S. bases and “other installations” without authorization. The Journal covered several examples, ranging from Chinese nationals entering a missile range in New Mexico to scuba divers found near a “rocket-launch site” in Florida.