Efforts by the US authorities to counter cyber-crime and terrorism have been criticised in an official report.
Homeland security has become a key issue in the US
It said the Department of Homeland Security's cyber-strategy suffered from poor coordination and communication, as well as an inability to set priorities.
The internal report warned that the US "still faces a number of challenges to address long-term cyber-threats and vulnerabilities."
It described cyber-terrorism as as one of the US's top five security threats.
The US Department of Homeland Security (DHS) created a new unit, called the National Cyber Security Division, to tackle net security in June last year.
The division was tasked with closing loopholes in government computer systems, responding to major incidents and making the country's critical infrastructure less vulnerable.
But the report from the DHS's inspector general, Clark Kent Ervin, makes gloomy reading for homeland security officials.
There are some positive comments, in particular for the creation of the cyber watchdog, US-Cert, and the establishment of a national cyber alert system.
But it goes on to highlight areas where the division has fallen short.
"Despite the progress made, DHS faces significant challenges in developing and implementing a program to protect our national cyber infrastructure," said the report.
It goes on to cite a failure to set priorities, identify how much money it needs long-term or develop a strategic plan to achieve its objectives.
The unit also comes under fire for poor communications and failing to provide effective leadership in issues of cyber-security.
The report said the division "must address these issues to reduce the risk that the critical infrastructure may fail due to cyber attacks."
"The resulting widespread disruption of essential services after a cyber attack could delay the notification of emergency services, damage our economy, and put public safety at risk," said the report.