The W54 is the smallest nuclear warhead to be deployed by the United States and the smallest known nuclear warhead in general. It is similar in size to a computer printer, with a diameter of 10.75 in (270 mm), about 15.7 in long (400 mm), and weighing slightly over 50 pounds (23 kg). The W54's low weight made it ideal for deployment with specially trained infantry units, such as those stationed in West Germany during the Cold War.
The W54 warhead can be fit in a large backpack, and a US Navy and Marines project in the mid-to-late 60s was developed to make use of this. Called the Special Atomic Demolition Munition (SADM) project, it involved a paratrooper descending to a target of value, such as a harbor, deploying the nuke, then swimming out to sea and getting picked up by a submarine or high-speed surface craft. Around this time the W54 package would be detonated and the target of value would go boom.
Another application of the W54 was in the Davy Crockett recoilless rifle, which was more like a mortar than a rifle. Operated by a three-man crew, nuclear-armed Davy Crocketts would be used to defend Europe from the Soviets if they invaded during the Cold War. These devices were dial-a-yield, meaning the yield could be set between 10 and 250 tons, enough to vaporize an area equal to several city blocks and deliver a lethal dosage of radiation to everything within 400 m, even at the lowest setting. With the W54, a team of just three American soldiers could have eliminated hundreds or even thousands of Soviet troops.