Cranes made by Shanghai Zhenhua Heavy Industries (ZPMC), a state-owned Chinese company, in some cases carry cellular modems, according to a congressional investigation reported by the Wall Street Journal on Thursday.
The modems offer a potential backdoor for remote access, and do not appear to support the normal operations of the equipment, the investigation found.
The discovery of the modems, which had not been previously disclosed, supports growing fears in US intelligence circles that Chinese cranes could be used to covertly monitor US ports, or even sabotage their operations.
Chinese firms make nearly 80 percent of the cranes used in US ports, after years of undercutting domestic suppliers on price.