Five years after Congress set a deadline for requiring all U.S.-bound shipping containers to be X-rayed overseas for nuclear weapons, customs officials have all but given up on the goal.

Customs and Border Protection officials scanned with X-ray or gamma-ray machines 473,380, or 4.1 percent, of the 11.5 million containers shipped in the fiscal year ended Sept. 30, according to the agency. That’s essentially the same percentage of containers that were scanned in 2007, the year a Democratic-controlled Congress required that agents start vetting every container.