The U.S.’s busiest container port for global trade foiled more than 120 million cyberattack attempts in August, fighting off a persistent threat to its operations as it grapples with shifting tariff policies.

The Port of Los Angeles identified intrusion, network exploitation, credential harvesting and malware attacks, among other efforts, Executive Director Gene Seroka told Bloomberg Television in an interview. The port’s cybersecurity operations team, in a coalition with private-sector businesses, have formed a seven-layer digital defense around its operations, he added.

Seroka’s comments came after U.S. officials disclosed that American government agencies were tracking cyber threats against nearly 20 ships around the world. Attacks in the maritime sector have escalated in recent years as vessels become increasingly dependent on digital systems for navigation, communications and other operations. 

“All they have to do is to get it right one time,” Seroka said. “This is front of mind every day.”

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Shifts in trade flows and policy have also impacted the port’s business, with the amount of cargo it handles from Southeast Asia increasing over the past year and a half and China’s share of total business shrinking. Vietnam’s business with the port has quadrupled over the past decade, while China’s has fallen to 40% of the port’s total throughput from 60% over the same period, he said.

The port has benefited from increased traffic, as ships divert away from the Suez and Panama Canals for security and weather-related reasons, Seroka said. Low water levels in the Panama Canal mean carriers from Asia are forced to unload cargo on the U.S. west coast and truck it overland to east coast markets. 

Having just completed its busiest three-month period on record over June-August, Seroka said the port could see a further 5% to 10% boost to volumes due to restrictions in the Panama Canal rerouting cargoes in its direction.