If a SGT comes under attack, unspecified security features in the vehicles give them, according to the NNSA, the capability to "surprise and delay even the most aggressive adversary".

The full range of defensive components in SGTs is unknown, but according to some media reports the vehicles are equipped with autonomous weapons systems and other "high-tech surprises" that allow them to independently engage and repel attackers even if all human crew have been killed or disabled.

[2][5][6] To frustrate easy identification of nuclear weapons convoys and deter potential hijack or attack, SGTs do not display any unique livery or other markings, and are purpose-built to mirror the appearance of civilian tractor-trailers.

While the trailer appears conventional from the outside, the back doors are over 12" thick, and an average-sized male can put their arms out from their sides and lay their palms flat against the wall.

In the event of an attack on a SGT, the TECC makes contact with predesignated state law enforcement agencies to assist in the defense of the vehicle.

[2][7] Until 2009 only one known, publicly available photo of a Safeguards Transporter existed, which was shot in 2005 by a private photographer as the vehicle was departing a naval station in South Carolina.