Cyber security is one of the USCG's top "common challenges", according to the military branch's annual security report.
"The dynamic nature of cyber security threats and the shortage of subject matter experts make cyber security preparedness and response a continuing challenge," the USCG said in the report.
On 27 July, a Cosco Shipping terminal at California's Port of Long Beach was hit by a ransomware attack. The incident did not affect port or terminal operations.
The report mentioned a June 2017 incident where multiple Maersk facilities worldwide were affected by a ransomware attack.
It pointed out that the occurrence caused Maersk to shut down operations at 76 terminals around the world, including five US locations.
"This incident was a clear reminder of the importance of cyber risk management in the MTS (maritime transportation system) both nationally and globally," the report said.
