On 2 May 1964, while "Card" was moored dockside in Saigon, a Viet Cong frogman planted an explosive charge that blew a hole in the hull, killing five crewmen. "Card" settled in of water. She was patched and pumped out, and raised on 19 May, and towed to Subic Bay, and then Yokosuka, for repairs. "Card" returned to service on 11 December. The attack has parallels to the suicide bombing of , in terms of being an example of "cost-effective" asymmetric warfare.