Since the Sept. 11 attacks, the U.S. has developed a sophisticated system of nets to catch dangerous foreign cargo before it gets into the U.S. The problem, critics say, is that the nets are full of holes. Those holes allowed a cargo container holding 22 Chinese stowaways to land April 4 at the Port of Seattle, unloaded from the M/V Rotterdam. The container likely would have sat for several days before anyone inspected it, said Mike Milne, a Seattle spokesman for U.S. Customs and Border Protection (CBP), the agency in charge of such inspections. Of course, long before that, in...