Updated

About $2.5 billion in federal grants paying for 10 years of security upgrades have made a huge difference at America's seaports in the decade since the 9/11 terrorist attacks.

The Port of Savannah, Ga., is the fourth-busiest container port in the U.S. Every day tractor trailers haul more than 4,000 cargo containers through radiation detectors. Similar scanners are installed at ports from coast-to-coast to look for nuclear bombs hidden in shipments.

Georgia's port security chief Kevin Doyle says before 9/11 there were wasn't even a complete fence surrounding Savannah's main terminal.

Susan Monteverde of the American Association of Port Authorities warns Congress could make deep cuts to port security grants in the 2012 budget.