A military police squad, several international police liaison officers (IPLOs
), and several host nation interpreters make up each PTT.
And eight years later Mr Corrigan's son, Martin - a member of the republican IPLO
- was shot dead by soldiers as he prepared an attack on police.
The 26-year-old who was a member of the IPLO
died on April 29 1992 after being shot by the UVF at Ligoniel Community Association.
In total the IRA killed 277, the INLA and IPLO
12 and loyalist terrorists eight.
The date was October 10, 1991, the day a loyalist had been shot dead by the IPLO
on the Shankill.
"The so-called Real IRA are operating here (in west Belfast) and in other areas along the same lines as the IPLO
The stand-off ended when the former IPLO
terrorist agreed to return to Dublin and not Belfast.
Some have associations with the UDA, the UDF or the IPLO