The commission examined dissident republican activity
Some former Provisional IRA members are helping dissident republican efforts to wreck the peace process, the paramilitary watchdog has said.
The Independent Monitoring Commission said the dissident republican threat was the highest for almost six years.
It said most new recruits were "inexperienced young males" but the involvement of former IRA members "significantly added to the threat".
Dissident republicans killed two soldiers and a policeman in March.
The body, which is responsible for monitoring paramilitary activity, delivered its 22nd report on Wednesday.
It also reported a
sharp rise in the number of beatings
carried out by loyalist paramilitaries.
The latest report covers the period from 1 March until the end of August.
The IMC said the two main dissident republican groups, the Real IRA and the Continuity IRA, were working more closely together to increase the threat posed to security forces.
It said a small number of former Provisional IRA members have given assistance to dissident republicans.
"This is not surprising following the dissolution of PIRA's structures," it said, adding that the vast majority have followed the IRA leadership and supported the peace process.
"The overall level of dissident activity was markedly higher than we have seen since we first met in late 2003," the report said.
"The seriousness, range and tempo of their activities all changed for the worse in these six months.
"During this period dissident republicans were violent and showed an intent to kill if the opportunity arose."
On 7 March, the Real IRA killed sappers Mark Quinsey, 23, and Patrick Azimkar, 21, at Massereene Army base in Antrim.
Two days later the Continuity IRA shot PSNI Constable Stephen Paul Carroll in Craigavon, County Armagh.
In the period covered by the report, there have been 11 attempts to kill other PSNI officers in Northern Ireland.
John Grieve, a member of the IMC, spoke at the report's launch in Belfast
The IMC said: "The three murders in March were by far the most serious incidents but there were many others involving extreme ruthlessness."
It added: "A number of the incidents for which dissidents were responsible demonstrated a capability to plan and organise which adds to the threat they present.
"They pose a major challenge to the law enforcement and other agencies on both sides of the border."
The group said dissidents remained committed to launching an attack in Great Britain if the opportunity emerged.
It said the devolution of policing and justice powers to the Northern Ireland Assembly would undermine dissidents and signal the strength of the political process.
The Independent Monitoring Commission was set up by the British and Irish governments in January 2004.