Hillary Clinton emails: UUP's Reg Empey nicknamed 'Empey Dumpty'
US officials appear to have referred to former Ulster Unionist leader as 'Empey Dumpty'.
During 2010 staff sent Ms Clinton news reports giving updates on Stormont talks on the devolution of policing and justice powers.
The subject line of one email to the then US secretary of state reads: "Latest news on NI. Empey Dumpty," apparently in reference to the nursery rhyme character Humpty Dumpty.
The attached news article refers to a meeting on devolution between the UUP and Sinn Féin's Martin McGuinness ending without consensus.
UUP assembly members later voted at Stormont against policing and justice powers being devolved to Northern Ireland following the Hillsborough Agreement.
Sir Reg Empey, who is now a House of Lords peer, had said his party did not believe the time was right for policing and justice to be devolved.
Meanwhile, in a briefing note to Ms Clinton at the time, US officials described Peter Robinson as "still exhibiting signs of weak leadership within his party".
The first minister replaced Ian Paisley as leader of the Democratic Unionists in 2008.
Ms Clinton's advisers said Mr Robinson was threatening to resign as first minister and trigger elections if the UUP did not vote in favour of devolving policing and justice.
However, they said the DUP leader still held the "key" to reaching an agreement on transferring powers from London to Belfast.
"Regardless of Empey's behavior, Robinson, who is still exhibiting signs of weak leadership within his party, still holds the key to the March 9 [date of assembly vote] outcome."