No question of a 'soft border' in 1989
Recent debates on whether there should be a "hard" or "soft" border in Ireland post-Brexit often refer to the situation during the Troubles.
Secret papers released by the Public Record Office show how things have changed in the past 25 years.
In December 1989, SDLP MP Seamus Mallon complained about the continued closure of the Newry-Dundalk road.
He said the closure on security grounds had resulted in the border "being cordoned-off for days at a time".
Drivers now barely notice the border as they pass through at high speed and on to the M1 motorway in the Republic.
Mr Mallon also complained that normal policing of the area was greatly inadequate as the Royal Ulster Constabulary (RUC) had "no stomach" for combating ordinary crime.
The duration of the road closures was intolerable, the MP wrote, given the "superb surveillance" facilities available to the security forces - a reference to the many Army watchtowers that peppered the hilltops of south Armagh.
Confidential papers from 1990 also shed some light on the current debate on free markets.
A letter from a Northern Ireland Office (NIO) official to Prime Minister Thatcher's private secretary shows government concern at the Irish government's "48-hour rule" for cross-border shoppers, introduced in 1987.
The regulations were introduced at a time when a substantial flow of shoppers were heading north to take advantage of lower prices.
The Irish measures denied these shoppers the 'travellers allowances' (ie freedom from Irish tax on Northern Ireland purchases) conferred by European law.
The NIO official stressed that the regulations were "transparently illegal" .
He reminded Downing Street that the British government had referred the case to the European Court, which had delivered its judgements "declaring against the Irish on all counts".
Northern Ireland Secretary Peter Brooke had urged the Irish government to comply with the court's ruling but they had delayed, citing consultations with the European Commission.
The official felt that if the Taoiseach, Charles Haughey, raised the issue in forthcoming inter-governmental talks, Mrs Thatcher might respond.
The perennial problem of cross-border fuel smuggling emerges in papers from 1990.
The Haughey government wanted the British to introduce a chemical marker into petrol on sale in Northern Ireland, while the NIO felt Irish estimates of the scale of smuggling were grossly exaggerated.
NIO official Austin Wilton noted that the fuel smuggling issue was first raised through the Anglo-Irish Secretariat in May 1989.
Irish officials had pointed to a link between cross-border fuel smuggling and "the financing of terrorism".
In the Republic a public inquiry was held into petrol prices, and Finance Minister Albert Reynolds was spearheading a drive "to smash cross-border petrol rackets".
To introduce a dye as demanded by Dublin would almost certainly require primary legislation at Westminster This could well be seen by some in the north as introducing a measure to benefit the Republic.
Restraint of trade?
There was also the question of the forthcoming Maastricht Treaty.
Mr Wilton asks whether "at this stage the (British government) wish to be seen taking a step which could be seen as restraining free trade?
"On the other hand, the Irish could argue that it was British ministers who urged than to take the smuggling problem seriously and that... they deserve (British) support."