One of the two men arrested, alleged republican militant Colin Duffy, has been charged with multiple murders over the past two decades, although he was never successfully convicted.
Details are still sketchy on who carried out the Oslo bombing, but Norwegian police are also connecting it to a gunmen who attacked a political youth camp shortly after.
Northern Ireland riots continued for a fourth night Wednesday. While violence has been on the wane, protests erupted in Belfast after a Protestant march went through the republican Ardoyne area.
Two men face their past three decades after the violence of the Troubles links their lives.