The nuke-in-a-box scenario — the fear that someone slip a nuclear weapon into the United States inside an ordinary shipping container — is an unlikely terrorist tactic. No intelligent enemy would take the world’s deadliest weapon, crate it up and wave goodbye. Too much could go wrong on a long, unsupervised sea voyage, jeopardizing the reliability and security of the warhead.

If a country was serious about wanting to attack the United States with nuclear firepower in a manner that would ensure surprise, leave no fingerprints and guarantee success, there’s a much easier, better and cheaper way. It’s one that could avoid the challenge of smuggling weapons into U.S. ports under the eyes of law enforcement, intelligence, customs officials and the Coast Guard: Put the missile on a ship disguised as a commercial freighter or private craft, sail near American waters and fire.

Any enemy could adapt a short-range missile, such as a Scud. Many already have them, and they know they work. The Scud has a large “throw-weight” (meaning it can carry a very heavy warhead) and could deliver a weapon at close range with ease. Building an improvised vertical launch platform for the missile is no significant technical challenge, nor is figuring how to make firing accurate enough to shoot a nuke at New York or Washington.

What’s better (from an enemy’s standpoint) is that the missile firing might well go undetected. Even tracing the perpetrator after the fact might be tough, particularly if the ship were scuttled after the firing. We wouldn’t know who to retaliate against.

Now that’s a real threat — one we should take seriously.

The folks at Lockheed-Martin have given it some thought. Recently, Heritage analysts visited the company’s innovation center in Norfolk, Va. One of the experiments we learned about was evaluating how to deal with a short-range ballistic or cruise missile concealed on a commercial vessel. The picture shown here portrays a mock-up of Chinese Silkworm cruise missile hidden in a horizontal launch tube disguised as a shipping container. Now if somebody actually tried this you would never find it because the U.S. only inspects containers bound for U.S. ports.