Violence which injured three police officers in Northern Ireland was probably orchestrated by dissident republicans, a senior police commander said.
Alan Todd, Assistant Chief Constable of the Police Service of Northern Ireland (PSNI), said he was not prepared to risk violence in order to save face after pulling his officers out of the New Lodge area of north Belfast.
The PSNI earlier pulled out following a stand-off with republican youths over an anti-internment bonfire.
The estate was then barricaded using metal fencing while teenagers held their hands up in triumph from on top the pyre.
Police had moved in earlier to facilitate contractors who were tasked with removing the structure.
Three officers were injured during sporadic bouts of violence.
Referencing the murder of journalist Lyra McKee by dissident republicans in Londonderry earlier this year during disturbances, Mr Todd said police did “not need to learn the lesson” of the risk to innocent bystanders.
Mark Lindsay, chair of the Police Federation for Northern Ireland, condemned the scenes.
He said: “Officers trying to protect the community and lawful agencies are once again caught in the middle and in the firing line.
“They are being attacked with a range of missiles and iron fencing.
“In one assault by a mob, one officer is seen to be struck and knocked to the ground.
“This behaviour is contrary to the overwhelming wishes of the people of New Lodge who do not want this bonfire or their area hijacked by young thugs.
“Our officers are acting with professionalism and restraint and we would urge those orchestrating these vicious and unacceptable confrontations to pull back before people are seriously injured.”
The bonfire is being built on land owned by Northern Ireland’s Department for Infrastructure.
It was due to be lit on Thursday night to mark the anniversary of the introduction of the controversial policy of internment without trial in 1971.
Earlier this week, politicians from both Sinn Fein and the SDLP said the people who live in the area do not want the bonfire.
Sinister graffiti appeared close to the pyre on Tuesday, threatening that if the structure is removed then a nearby community centre will be targeted.
The graffiti is also set to be removed by council workers.
A spokesman for Belfast City Council said it would “endeavour to remove the contentious graffiti as soon as practicably possible”.
Operation Demetrius in 1971 saw hundreds arrested across the region on suspicion of being involved with paramilitary groups.
The vast majority arrested were nationalists, although a significant number of them had no connection with the IRA.
The anniversary has traditionally been marked by many from the nationalist and republican tradition with bonfires, although recent years have seen a move away from pyres towards community-based diversionary activities.
The New Lodge is a mainly nationalist area dominated by decades-old public housing blocks.
The bonfire is made of wooden pallets and has an Irish tricolour flag on top.