Irish government officials complained to US diplomats about the London government being too soft on Peter Robinson.
They were left angered by demands from the DUP leader during the tense negotiations to transfer policing and justice powers to Stormont.
The incident, detailed in a leaked diplomatic cable, centred on Mr Robinson’s comments that abolishing the Parades Commission was a pre-condition for any deal.
Officials in Dublin complained that the British had been “too easy” on Mr Robinson, and warned of frustration over his hardball strategy.
Another part of the document details how Martin McGuinness was offended after learning that Secretary of State Shaun Woodward had privately complained about him being “problematic” to US representatives.
The confidential dispatch was written in December 2009, and gives a rare glimpse into the delicate position as the parties pushed for a deal.
Reporting back to Washington, US Ambassador to Ireland Dan Rooney warned the situation was “dicey, with a real chance of failure”.
Four weeks earlier, Mr Robinson had publicly warned that removing the Parades Commission was a necessary step to “increase confidence” in devolved powers.
The move angered Sinn Fein, with Gerry Adams claiming afterwards that it was “totally and absolutely unacceptable” to link the issues.
His comments received sympathy from Irish government officials during a subsequent meeting with US diplomats.
According to the cable, Kevin Conmy from the Department of Foreign Affairs and Paul McGarry from the Taoiseach’s office both expressed irritation at Mr Robinson.
“Both of our interlocutors reported frustration on the Irish side with Northern Ireland First Minister Peter Robinson,” the cable stated.
“Having any precondition for devolution was unacceptable to Sinn Fein and rightly so, as Sinn Fein had stuck by its side of the bargain on devolution.”
Later in the cable, and accompanied by the words “strictly protect”, both officials criticised the UK government.
“Both Conmy and McGarry (STRICTLY PROTECT) opined that the British had been too easy on Robinson, in effect allowing him to link parades with devolution,” it adds.
According to the cable, both Mr Conmy and Mr McGarry warned the devolution of policing and justice must be isolated from other issues, especially parades. They also expressed concern that Sinn Fein might leave the Executive and force early elections if Mr Robinson did not commit to a start date over devolution before Christmas.
Another part of the document details how Mr McGuinness was offended after learning that Mr Woodward had privately complained about him.
It reports: “Conmy (STRICTLY PROTECT) said Northern Ireland deputy First Minister Martin McGuinness was upset about Northern Ireland Secretary Shaun Woodward’s actions on a trip to the U.S.
“Woodward apparently complained to US interlocutors about McGuinness, being problematic.
“The Americans had then called ‘their friends in Sinn Fein’ to report that.”