A waiver implemented by former Secretary of the Department of Homeland Security (DHS) Janet Napolitano that has exempted DHS from scanning every piece of cargo that enters the U.S. from international seaports will expire in a few months. We can only hope that her successor, Jeh Johnson, renews this waiver.

In 2007, Congress mandated that DHS be able to scan all cargo from foreign seaports with radiation detection equipment by July 1, 2012. The same law allowed the DHS Secretary to extend the deadline by two years, which Napolitano did in 2012—and for good reason.

The U.S. imported goods valuing roughly $2.3 trillion in 2012, or about 17.5 million 20-foot equivalent container units; 55 percent of that total value—and over 99 percent of total import shipping weight (roughly 720 million tons)—was from sea-based imports.

To her credit, Napolitano realized the sheer goliath of a task it would be to fix every port with the equipment and personnel necessary to scan every single piece of cargo on every ship—roughly $16.8 billion for all shipping lanes. The shipping delays it would cause would result in an estimated $500 billion in total profit loss. And even if there were a feasible way to scan all cargo with little cost to businesses and taxpayers, the data collected would be so immense that it would be useless to DHS anyway.

There are easier, more effective ways of securing U.S.-bound cargo. This is where risk-based approaches such as the Container Security Initiative and the Proliferation Security Initiative come in. They encourage private-sector involvement, target high-risk containers, and ultimately dissuade the trafficking of weapons of mass destruction to begin with. As James Carafano, Heritage’s vice president of foreign and defense policy studies, was recently quoted as saying, “Nuclear smuggling and nuclear terror require a lot of money, a lot of effort and a lot of infrastructure.”

So despite some Representatives having scolded DHS for not implementing the cargo screening mandate, Congress should perhaps focus more on keeping the needle out of the haystack before it ever gets thrown in.