Another problem is that operational performance of the system has been nixed, the GAO said.

"ACE releases one through four are in operation. To date, these releases' operational performance has been uneven," the GAO said. "For example, ACE has largely been meeting its goals for being available and responsive in processing virtually all daily transactions, and has decreased truck processing times at some ports. However, ACE is not being used by as many CBP [Customs and Border Protection] and trade personnel as was expected, and truck processing times at other ports have increased. Moreover, overall user satisfaction has been low."

In addition, the GAO said because the DHS has not fully defined the goals and benefits of the system, it remains unclear whether ACE will meet its goals of supporting border security by enhancing analysis and information sharing with other government agencies and streamlining time-consuming and labor-intensive tasks for Customs personnel and the trade community through a single Web-based interface.

To ensure the success of the system, the GAO recommended that the DHS develop realistic ACE performance measures and targets; align them with ACE program goals, benefits, and desired business outcomes; and minimize concurrent development of ACE releases. The DHS agreed with the GAO's recommendations and said it was taking steps to address them.