The GAO is concerned about how we're securing our energy imports, especially those like oil, liquefied gases and jet fuels brought via tanker from across the oceans.
Released Wednesday by the office, the report states that, with 55 percent of the national crude oil supply arriving by tanker, the fuel supply is especially vulnerable to terrorist attacks.
Specifically, the GAO cited the threat of boat-based suicide attacks on U.S.-bound tankers, or even "standoff attacks" that could threaten U.S. energy security.
The issues, according to the GAO isn't solely one of disrupting the U.S. oil supply, but with refined products and highly-explosive liquefied gases, attacks on these vessels could affect nearby persons, especially if such attacks were made in harbors and ports.
The GAO said that the problem is compounded by the fact that compliance standards for protection haven't been globally accepted. The office also noted that response plans don't always recognize there are two essential plans that must be put in place in the event of such an attack: spill response plans and security response plans.
The full GAO report can be downloaded (PDF document) at www.gao.gov/new.items/d08141.pdf.