Biden on Tuesday reiterated America's "commitment to preserving peace and prosperity" in Northern Ireland. Despite the outbreaks of violence in Derry and the alert of "severe risk" for terrorist attacks, the US president said he felt "more than comfortable" with his expected visit to the land of his ancestors.

The possibility that Biden's visit will serve to unblock the political paralysis in Ulster is however rather remote, given the scepticism traditionally aroused in the unionist ranks by the influence of the Irish lobby in Washington.