The Navy is investigating the disappearance of 20 concussion grenades from the San Diego-based destroyer Pinckney, according to a Navy official briefed on the incident.

The missing ordnance turned up missing during an inventory inspection, said Lt. Cmdr. Rebecca Haggard, spokesperson for Naval Surface Forces Pacific.

Haggard would not confirm or deny that the missing ordnance was 20 grenades, citing anti-terrorism force protection policy.

"While conducting an inventory accounting review during a Shipboard Explosive Safety Inspection, USS Pinckney (DDG 91) Sailors discovered ordnance was missing," Haggard said. "Immediately after determining the missing inventory could not be otherwise accounted for, the ship conducted two subsequent comprehensive ship-wide inventories and found no other discrepancies. The ship contacted the chain of command and NCIS to initiate an investigation."

Pinckney is currently undergoing maintenance pier-side.