The PSNI has come under fire for failing to stop a number of dissident republican shows of strength.
Masked men and women openly paraded through the streets of Lurgan, north Belfast, Coalisland and Londonderry over the past three days.
In one of the most sinister displays a threat from the Continuity IRA against members of the security forces was read out by masked men in Lurgan.
Unionists have criticised police for not taking any preventative measures to stop the paramilitary displays.
However, last night PSNI Chief Constable George Hamilton used social media to hit back at some of the critics. Responding to negative comments on Twitter, Mr Hamilton wrote that his officers could hold their heads high, "despite commentary from uniformed naysayers".
He added via his Twitter account, "officers have done an outstanding job #proud."
Earlier Assistant Chief Constable Stephen Martin also defended the policing operation of the illegal parades which saw dissidents wearing military garb, dark coloured berets and sunglasses openly march in Ardoyne, Londonderry, Lurgan and Coalisland across the Easter weekend.
Ulster Unionist councillor Colin McCusker has demanded to know what preventative measures were taken to stop the paramilitary show of strength in Lurgan on Saturday.
"I was well aware that this was more than likely to happen - if I knew, the PSNI knew too. I would like to know what preventative measures, if any, were taken to stop this happening," he said.
"In recent weeks the finger has been pointed at the loyal orders by some claiming that by the Apprentice Boys holding their annual Easter Monday demonstration in Lurgan this year, a parade which has been properly notified under the law, they are stretching police resources, but an unnotified parade which was basically a display of terrorist thuggery goes unpunished.
"Those involved in the parade are relics of the past and should be shunned for the pathetic cause which they desperately cling to."
DUP MLA and Policing Board member Jonathan Craig said: "I am extremely surprised that the intelligence hasn't allowed them (the PSNI) to pre-empt these events.
"Serious questions will have to be asked over what will be done to ensure that those who organised and carried out these events are arrested and prosecuted."
ACC Stephen Martin said that suspected breaches of Parades Commission determinations in Coalisland and unnotified processions in Ardoyne and Lurgan are being investigated.
He also said most events over the Easter weekend had passed off peacefully.
"In policing all events over the Easter weekend our overriding desire is to ensure that commemorative occasions, parades and protests pass off lawfully and peacefully," he said.
"Our focus is on keeping communities safe and our job, with a few notable exceptions, has been made that much easier because of the responsible attitude of all parties concerned.
"We are, however, investigating suspected breaches of Parades Commission determinations in Coalisland and unnotified processions in Ardoyne and Lurgan. We have gathered evidence at these events and will present reports to the Public Prosecution Service with a view to holding individuals accountable."
On Saturday around 20 dissidents marched through the Kilwilkie estate to St Colman's cemetery in an illegal parade during which a masked man read out the Proclamation and then threatened to use violence against "British forces".
A low-flying police helicopter observed events. Another illegal parade took place in Ardoyne on the same day organised by the Republican Network for Unity.
On Sunday around 50 dissidents wearing military clothing, berets and dark sunglasses appeared in the area of the main Coalisland parade.
Yesterday, another group wearing military uniforms and disguising their identity appeared during a parade at Derry City Cemetery. A statement from dissident prisoners held at Maghaberry jail was among the statements read out.
First Minister Arlene Foster said: "I want to see these people behind bars. No place for masked men in Northern Ireland. Police assure me that evidence has been gathered. It's clear that the Parades Commission determination has been breached."