Port security a thimble of prevention in an ocean of cargo.(Knight Ridder Newspapers)

WASHINGTON _ Last October, Italian investigators stumbled on every U.S. port security officer's nightmare: a suspected al-Qaida terrorist hiding in a transatlantic shipping container. He had two cell phones, a laptop computer, a Canadian passport, airport maps and a U.S. airport security pass.

Foiling such threats is a needle-in-a-haystack problem, as are most post-Sept. 11 concerns about port security. Six million cargo containers pass through American ports every year and U.S. Customs searches only 120,000, a mere 2 percent.

Compounding the problem, nearly everyone _ port security planners, shipping companies and the industries that rely on them _ insists that any new counterterrorism measures shouldn't slow the flow of foreign trade, 95 percent of which comes or goes by sea.

Before much can be accomplished, bureaucracies must be unsnarled. The Coast Guard deals with ships at sea and their routes into harbor. Custom officials inspect ships' cargoes once they reach U.S. ports. The Immigration and Naturalization ...