Published Saturday, 12 July 2014
The memorial was also attacked in June. (© UTV)
Police say they are treating the incident, which was reported in the early hours of Saturday morning, as a sectarian hate crime.
A PSNI spokeswoman said paint was thrown at the memorial at White Brae in the Ligoniel Road area of the city shortly after 12.05am.
"Damage was caused and enquiries are continuing," she said.
Last month the stone and poppy wreaths were also damaged in a separate attack.
The Royal British Legion says the monument has been targeted many times in recent years.
The murders of the soldiers were seen as one of the key points in Northern Ireland's descent into full-scale violence in the 70s.
Police have appealed for information.
Condemning the attack, DUP councillor Lee Reynolds said: "No doubt this latest attack was deliberately timed to coincide with the Twelfth of July celebrations.
"Those responsible seem determined to cause upset and hurt for the families of these three soldiers and for all who have supported this memorial.
"They succeed only in portraying themselves in the worst possible light."
Sinn Féin councillor Gerry McCabe said: "Unfortunately this isn't the first time this monument has been defaced. I condemn unreservedly those behind this attack, it is wrong.
"If anyone has any information on who is behind these wanton acts of vandalism then I urge them to immediately contact the PSNI."
© UTV News