Ian Paisley tried to get around being barred from the US by asking the United Nations secretary general for an interview.
The former Northern Ireland first minister had a visa revoked three times in 1981 and 1982 as he attempted to get into America and put the unionist version of the Troubles across.
At the time, the US state department said the decision to stop Mr Paisley at the border was based on his "near advocacy of violence".
But according to documents released under the 30-year rule by the Department of Foreign Affairs in Dublin, diplomats were told privately that it was more about him personally than his policies.
One surprising note in the file, however, is that the embassy in Washington claimed firebrand unionist Mr Paisley as Irish.
Official Jimmy Sharkey warned officials in Dublin in early 1981 not to intervene in any visa row for fear of being seen to silence the DUP chief.
He wrote: "Paisley in terms of our law is an Irish citizen.
"For us to try and block his admission would only enhance his publicity... there would be dangers of a highly damaging misrepresentation if we were to move.
"We would feel that Paisley would have the elementary good sense to keep the Pope out of his remarks when in the USA and to present a political message, however hardline."
Another letter from Irish officials says that if the US allows Mr Paisley in, that "we would particularly hope that he would be denied political recognition as by, for instance, being received by the President".
But on January 6 1982, Mr Paisley attempted to flank America's immigration chiefs by sending a telegram to UN secretary general Javier Perez de Cuellar seeking an interview with him later in the month.
The prospect of the UN being dragged into the Northern Ireland question greatly exercised British diplomats in New York and London, as one Irish official wrote to colleagues in Dublin, London and Washington: "The UK Permanent Representative was disturbed by the possibility of the NI issue being raised at the UN and the likelihood that other groups would follow Paisley's lead."
The diplomat also suggested UK authorities would do "everything possible" to stop Mr Paisley visiting the Turtle Bay headquarters.
According to the cables out of the US, Irish diplomats appeared much more relaxed, suggesting the secretary general would not agree to an interview with Mr Paisley. Even if he did, they were convinced that would not secure him a visa.
Publicly, the US authorities said Mr Paisley was refused a visa because his activities may be prejudicial to the country's interests.
Privately they told Irish embassy staff it was because of his "near advocacy" of violence, his public statements and the establishment of the Third Force - attempts by Mr Paisley to create a militia in Northern Ireland of up to 100,000 unionists.
The US state department was forced to deny that heavyweight Irish-Americans - speaker Tip O'Neill and senators Ted Kennedy and Daniel Moynihan - influenced its decisions.
They also insisted that its review of the visa application began before congressmen showed an interest.
Some documents show Mr Kennedy's office pressed the Irish embassy to get Dublin to fight against the visa application, while cables monitored the reaction in the US press at that time.
Bob Jones Jnr, the chancellor of the South Carolina university where Mr Paisley got a doctorate, told the Washington Post the decision was down to Catholic bigotry.
Mr Paisley went to Canada in January 1982 while his wife Eileen went to the US with a unionist delegation involving Peter Robinson and John Taylor.
The mood was angry, with the group claiming they had been ignored by Mr Kennedy and only offered a meeting with junior figures in the Irish-American senate camp.
"The US side viewed this meeting with the Unionists as being not very useful and a waste of time. It was their impression that the overall visit to the US had not been very productive for the Unionists," the embassy wrote.
"While they made few converts to the Unionist cause they may have served a useful purpose in educating some of the more emotional Irish-Americans to the fact that the Unionist viewpoint is also strongly held and that it cannot be ignored."