Former first minister Arlene Foster promised Donald Trump a 'warm welcome' in Northern Ireland
The letter penned by then first minister Arlene Foster and deputy first minister Martin McGuinness was sent in the wake of the billionaire's shock election victory in November.
The invite emerged today, hours before a planned protest at the US consulate in Belfast to voice opposition against Donald Trump's controversial executive order that has temporarily barred citizens from seven mainly Muslim countries entering the US.
Since the letter was sent, the Stormont Executive has imploded amid a green energy scandal.
Mrs Foster and McGuinness are no longer in ministerial office and the region is heading to the polls for a snap election in March.
The letter congratulated Mr Trump on his election victory and noted Northern Ireland's "strong historical, economic and political ties" to the US.
Theresa May has extended an official invitation for President Trump to visit the UK
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US President Donald J. Trump attends a meeting on cyber security, in the Roosevelt Room of the White House, in Washington, DC, USA, 31 January 2017
"We are proud to say that the United States is our largest inward investor and we believe that our relationship has proved mutually beneficial for both your great country and our small but dynamic region," the minister wrote.
They concluded: "We wish you every success in your new role and we extend an invitation to visit Northern Ireland. You can be assured of a warm welcome."