The Sinn Féin President has described terrorism as ethically indefensible and has said that those responsible for the attacks on the US must be brought to justice.
Speaking at his party's Árd Fheis in Dublin, Gerry Adams also said that the United States terror attacks of 11 September have set back the causes of other struggles around the world.
Speaking on the Northern peace process, Mr Adams said that the weapons decommissioning issue could be solved, but he did not believe it would be resolved on the basis of threat, veto, or ultimatum.
He blamed the British government for the crisis in the peace process but said that recent moves by Republicans pointed the way to a future free of IRA guns.
He accused Sinn Féin's critics of hypocrisy, claiming they had focused solely on vilifying Republicans while over 250 Loyalist bomb attacks took place in the North and Catholic girls in north Belfast were blockaded on their way to primary school.