While paramilitary-style killings in Belfast proved the prime influence on Dublin ministers, information uncovered in nationwide police moves also affected the decision to reverse the freeing of nine IRA men.
The month-long police operation - code-named Mid-West - headed off plans by IRA units to steal in-transit cash shipments. At least two raids were foiled by the police activity, detectives believe.
The information was passed to the government in Dublin and is understood to have played a part in the blocking of the scheduled permanent releases late on Thursday.
Sixteen prisoners listed as subversives - including the IRA nine - will be among 390 Irish inmates to be granted temporary freedom over Christmas.
One of the IRA group is Thomas McMahon, convicted of the IRA murder of Earl Mountbatten of Burma 16 years ago.
The Sinn Fein vice- president, Pat Doherty, said the decision not to release the nine permanently was a "disservice" to the Northern Ireland peace process. "To be cancelling the release of prisoners at Christmas and inflicting hurt on their families because of incidents in Belfast is absolutely disgraceful. There is no logic to it," he added.