Long Beach, California — Los Angeles and Long Beach are home to the largest port complex in the Western Hemisphere. Last year, 40% of the nation’s imports, worth nearly $500 billion, passed through the ports in more than 20 million containers, according to L.A. and Long Beach port officials.

Each shipping container gets offloaded by towering cranes up to 400 feet tall. In some U.S. ports, they’re automated, and that has Gary Herrera, president of the local longshoremen’s union, worried. 

 “You wouldn’t even have to go to war to destroy our economy,” Herrera said. “You could shut down these ports right here.” 

He says the automation was designed to help cut costs, but it also makes the cranes highly vulnerable to hacking.  

“When you have a robot, and we don’t have the ability to go over and override that, we become at the mercy of whoever’s on the other side controlling that robot,” Herrera added.

In this case, “the other side” is Shanghai Zhenhua Heavy Industries Company, or ZPMC, a Chinese state-owned military contractor that built 80% of the ship-to-shore cranes at U.S. ports. A yearlong congressional investigation found that everything these cranes do can be monitored by the Chinese government. Some ZPMC cranes can even be controlled remotely, and in a worst-case scenario, shut down entirely, according to the investigative report. 

“Our supply chain for food would be disrupted. Think of empty shelves on grocery stores, think of manufacturing grinding to a halt,” said Rep. Mark Green, a Tennessee Republican who chairs the House Committee on Homeland Security.

Green said the joint congressional investigation uncovered unauthorized cellular modems hidden on some ZPMC cranes that could bypass port firewalls.

“These weren’t in the design specs, and they got placed in there without telling anybody,” Green said.

In a statement, ZPMC told CBS News its own investigation “failed to find any evidence” of the hidden modems. The company says the congressional report “is based on unfounded claims,” and maintains that it does not have the capability, intent or motive to disrupt or stop the operation of any U.S. port.

But China’s access to the cranes could even impact the U.S. military, according to Chris Krebs, a CBS News consultant and chief public policy officer for the cybersecurity firm Sentinal One. 

“The hairs on the back of my neck standing up when I talk about this,” Krebs said. “It is the number one cyber risk facing the United States right now.”

“They’d hit a port, particularly on the West Coast, because that’s how we move material, that’s how we move equipment,” Krebs went on. “That’s how, in some cases, we’re gonna move personnel. The Chinese are preparing for war. Are we?

In Long Beach, partially-automated ZPMC cranes work around the clock. Port CEO Mario Cordero says he hasn’t seen any problems with them.

“If a port was to shut down, you’re looking at a $2 billion hit a day in the local economy,” Cordero said.

Cordero believes ports should consider moving some operations back to a more manual system.

“Would I want a completely automated terminal? Because of the security issues, I think the answer in today’s world is no,” Cordero said.

The Biden administration committed $20 billion to upgrading port security and beginning the replacement of ZPMC cranes. The Trump administration told CBS News they want American made equipment to handle cargo at U.S. ports.