Barack Obama's Irish-American anti-terrorism chief will be by his side as the US president touches down in Dublin today.
John Brennan, who played a key role in advising Mr Obama on the assassination of Osama bin Laden, does not normally accompany the president abroad.
But sources last night said he is "excited" by his trip to the country of his own ancestors.
Mr Brennan's parents hail from Co Roscommon, where he still has family and has visited on a number of occasions.
He normally stays in Washington when the president is abroad. However, White House officials last night said Mr Brennan has "gone out of his way to be a part of this trip".
The 55-year-old former CIA spy briefed the US media following the Navy Seal mission, which resulted in the death of Bin Laden.
Mr Brennan's full title is Deputy National Security Advisor for Homeland Security and Counterterrorism, and Assistant to the President.
He is just one of the prominent Irish-Americans in the White House, along with chief of staff Bill Daley, national security advisor Tom Donilon and deputy national security adviser Denis McDonagh.
White House deputy assistant to the president, Ben Rhodes, said there are several Irish-Americans working in the West Wing who remind Mr Obama of the influence of their ancestral home.
"He relies every day on Irish-Americans and I can tell you the Daley and Brennan and Donilon cabal here in the White House make sure to remind him he needs to note the contribution of Irish-Americans."