The third USNS Mercy (T-AH-19) is the lead ship of her class of hospital ships in the United States Navy. Her sister ship is the USNS Comfort (T-AH-20). She was named for the virtue of compassion. In accordance with the Geneva Conventions, USNS Mercy and her crew do not carry any offensive weapons, though defensive weapons are available. Firing on the Mercy would be considered a war crime.