The Ulster Defence Association (UDA) is a Northern Irish Loyalist paramilitary organisation outlawed as a terrorist group in the UK and Republic of Ireland, which is perceived by its supporters as 'defending' the 'unionist community' from Irish nationalism. The group has been involved in guerrilla warfare against Republican paramilitaries, including assassinations, as well as attacks on and murders of Republican and Catholic civilians.

It also is accused by opponents of racketeering and of involvement in the drugs trade in Northern Ireland. The US State Department's 2002 "Patterns of Global Terrorism" report substantiates these accusations, stating: "The UDA/UFF has evolved into a criminal organization involved in drug trafficking and other moneymaking criminal activities."

The UDA was formed in 1971 as an umbrella organisation for various loyalist vigilante groups. It originally had the motto 'law before violence' and was in fact a legal organisation until it was banned in August 1991. During this period of legality, the Ulster Freedom Fighters (UFF) committed a large number of murders. It is widely believed that the UFF was simply a cover name for the UDA. Today the two organisations are more or less indistinguishable.

They have been involved in a feud. On February 22 2003 it announced a 'complete and utter cessation' of all acts of violence for one year. It said it will review its ceasefire every three months. It also apologised for the involvement of some of its members in the drugs trade.

Its 'ceasefire' was welcomed by the Northern Ireland Secretary of State, Paul Murphy and the Chief Constable of the Police Service of Northern Ireland, Hugh Orde. Some republicans, however, were sceptical, claiming that the UDA had a history of 'telling lies' and that its word could not be trusted.

The Red Hand Defenders is an organisation that formed in 1998. Its members are loyalist hard liners that oppose the ceasefire. The organisation seems to be made up of members of the UDA/UFF and LVF - all organisations that officially denounce them. Speculation remains as to what exactly what their relationships are.