Three bombs were found and destroyed on Montrose beach on Monday.
The alarm was raised by a member of the public walking on the beach who contacted Aberdeen Maritime Rescue Coordination Centre.
A further search by Montrose Coastguard found several other pieces of ordnance.
The Royal Naval Explosive Ordnance Disposal division from Faslane was requested to attend the scene to make the items safe. They carried out a controlled explosion at around 6.25pm.
A Coastguard spokesman said: “A member of the public walking on the beach reported this at 9.15am on Monday. The object had been found high up on the beach.
“Our team found more items of ordnance and we alerted the Explosive Ordnance Disposal division from Glasgow, who arrived at about 5pm.
“They determined that the items were suspicious enough to blow them up, rather than just remove.”
The spokesman said they did not know if the bombs were of a World War II vintage.
He added: “Most of the time it is stormy weather that washes these items on to the beach.
“If people find items that are in any way suspicious, they should alert the authorities.
“If an item is found below the high water mark they should call the Coastguard. If it’s above the high water mark they should contact the police.”