Britain's Queen Elizabeth II is to meet a former IRA commander, Martin McGuinness, during her visit to Northern Ireland next week.
McGuinness, now a Sinn Fein politician, is the deputy first minister of Northern Ireland. The meeting is being seen as highly symbolic.
Sinn Fein President Gerry Adams confirmed that McGuinness will meet the queen at an event in Belfast to celebrate art and culture across Ireland.
"Because this involves Martin meeting the British monarch, this will cause difficulty for Republicans and nationalists who have suffered at the hands of British forces in Ireland over many decades," he said in a printed statement.
However, the party had agreed that McGuinness should meet the queen "in the context of conflict resolution and national reconciliation, as well as our own republican national objectives," he said.
The event is not connected with the queen's diamond jubilee celebrations, he said.
"This is a significant initiative involving major political and symbolic challenges for Irish republicans," Adams added.
"As the record of the peace process demonstrates, Irish republicans have frequently been prepared to take bold and historic initiatives and risks for peace to break stalemates and find agreements."
The meeting follows the queen's historic visit to the Republic of Ireland in May of last year.
It was the first visit by a British monarch to the republic since it gained independence in 1921 and marked a reconciliation between neighboring countries, who once viewed each with suspicion and hostility.
An IRA bomb killed one of the queen's relatives, Lord Mountbatten, in 1979. IRA members have also killed police officers and soldiers in Northern Ireland, who serve in the queen's name.
The nationalist community in Northern Ireland sees the British as occupiers and wants their rule in the province to end.
McGuinness has admitted that he was a leader of the Provisional IRA during the 30-year conflict in Northern Ireland between pro-British and pro-Irish forces.
In recent years, he has received death threats from hard-line dissident IRA splinter groups because of his support for the peace process.
He stood for Ireland's presidency last year but returned to his post as deputy first minister of Northern Ireland when his campaign was unsuccessful.
Accepting his party's nomination last September, he said republicans have an obligation to "heal the wounds of their actions."
The majority of the island gained independence in 1921, following two years of conflict, but six of the nine counties of the province of Ulster chose to stay in the United Kingdom, eventually becoming the country of Northern Ireland.
In the late 1960s the conflict between mainly Protestant unionists who want Northern Ireland to remain part of the United Kingdom and largely Roman Catholic nationalists who want the North to be reunited with the rest of Ireland exploded into a political and sectarian war, known as the Troubles.
The three decades of ensuing violence between the IRA and loyalists claimed the lives of more than 3,000 people, most of them north of the border, and while the Good Friday Agreement of 1998 effectively ended the conflict, suspicions remain. For this reason the queen's state visit is more than symbolic.
Under the terms of the landmark accord, terrorist groups on both sides dumped their weapons, and political allies of the two now work together in Northern Ireland's power-sharing government.