The DUP has said it has been promised access to secret intelligence on the IRA and loyalist paramilitaries from MI5 and other security agencies.
Peter Robinson and Ian Paisley are both now members of the Privy Council
The party has said the move will help it judge whether republicans remain committed to peaceful means.
It has previously relied on the IMC to hold the IRA to account.
The move has been made possible by the appointment of two more DUP members to the privy council, which gets secret briefings on national security issues.
Peter Robinson and Jeffrey Donaldson are the new members of the council, which is one of the oldest parts of government.
The party leader, Ian Paisley, is already a member.
The three DUP men will also be appointed members of a new security committee being set up by the DUP at Stormont.
The party has said they have been told they will be entitled to intelligence briefings by the security services.
SDLP leader Mark Durkan said appointments to the Privy Council "should not be made on the basis of a party political contrivance".
"This plan is not in the spirit of the events of yesterday," Mr Durkan said.
"This step corroborates the concerns we have consistently expressed about British Government plans for MI5 in Northern Ireland including what was agreed at St Andrews (political talks)."