America’s largest commercial ports have failed to build up defenses against potential cyber attacks, a new study contends, raising concerns about the vulnerability of computer networks that help move energy, food and other goods to market, the Los Angeles Times reports.

Coast Guard Commander Joseph Kramek, who spent a year as a fellow at the Brookings Institution examined the Los Angeles and Long Beach; Baltimore; Houston and Beaumont in Texas; and Vicksburg, Miss., on the Mississippi River, and his research shows that the level of cyber security awareness and culture in U.S. port facilities is relatively low.

The ports of Los Angeles and Long Beach have taken some defensive steps – Los Angeles used a $1.6-million grant to protect its computer networks from hackers. Long Beach spent $35 million to build a secure communications infrastructure.

Authorities at the studied ports dispute some of the study’s claims and conclusions.