An RUC operation to ensure Catholic children in north Belfast can walk to Holy Cross school along their traditional route will continue whatever the cost, a senior officer has said.
Assistant Chief Constable Alan McQuillan said he was not considering rerouting the children away from the Protestant Glenbryn estate to a back entrance of the school.
"We have made it absolutely clear at every stage these children have the right to get to the school by this direct route and we will do everything humanly possible to facilitate that," he said.
This week's security operation to ensure safe passage for the children and their parents is expected to cost more than £500,000 sterling.
Mr McQuillan said: "The bill for police overtime alone is between £40,000 and £50,000 per day, so a quarter of a million a week for that alone".
He said Wednesday's pipe bomb attack, in which four officers were injured, was probably not aimed at school children.
"There were some people there who if they could have thrown that bomb at the children they would have, but the primary target I believe was our officers," he said.
Mr McQuillan said he had no doubt that loyalist paramilitaries had been involved in the school protests.
The police are treating death threats against three women whose children attend Holy Cross very seriously, Mr McQuillan said. The Red Hand Defenders, a cover name used by the UDA and the LVF, said they would kill the women if they walked their children to school.
Yesterday's relative calm in Ardoyne was, he said, due to people drawing back after seeing pictures of Wednesday's bomb.
"The mood I sense is that the vast majority of people in the Protestant community in Ardoyne may have some sympathy for this protest but they do not want to see their community destroyed by this violence."