A Garda and a senior British officer have both told the Smithwick tribunal an operation which led to the deaths of two senior RUC officers was already underway by the IRA before the men arrived in Dundalk garda station.
The tribunal was set up to look at allegations that a garda leak led to the deaths of chief superintendent Harry Breen and superintendent Bob Buchanan on their way back from the visit to Dundalk garda station on 20 March 1989.
Brigadier Ian Lisles, who also served for several tours in Northern Ireland, was posted to South Armagh a few months after the ambush.
He said the operation would have been impossible to carry out in less than three hours, because of the time needed to assemble men and weapons.
The time is the absolute minimum,” he said. “You’d probably want five to eight hours ideally.”
Retired garda sergeant Bernard McGrath also said it was “highly iomplausible” the IRA could mount the operation on short notice, and estimated it would take “a matter of days”.
The tribunal was set up to look at allegations that a garda leak led to the deaths of chief superintendent Harry Breen and superintendent Bob Buchanan on their way back from a visit to Dundalk garda station on 20 March 1989.
The tribunal has previously heard that the two men arrived in Dundalk just after 2pm, and left at about 3.15pm.
But IRA activity was already happening by 2.30pm on the road where the ambush took place.
The meeting was agreed in a telephone call over an open line between the RUC and Dundalk garda station at 10.30am that morning.
“It’s a very ambitious time limit,” retired brigadier Mike Smith said.
The brigadier said he could not comment on reports that the British army and RUC has noticed an increase in radio traffic along the border from midday on the day of the ambush.
Brigadier Smith served seven tours of duty in Northern Ireland during his career between 1971 and 1997, although he was not there in 1989 when the ambush took place.
He was called to give expert evidence on the IRA tactics used in the ambush based on his experience in Northern Ireland.
Earlier, the tribunal was told that statements from witnesses would only be circulated to the legal teams of people mentioned in them, and not to all legal teams at the tribunal.
This was a security precaution at the request of several retired RUC special branch members, barrister Justin Dillon said.
The chairman assured the legal teams that he would read all statements and ensure they got notice if any of their clients were affected.