The chairman of the Independent International Commission on Decommissioning, Gen John de Chastelain, has said he is optimistic that the paramilitary organisations in Northern Ireland will hand over arms within two years.
An amnesty for the decommissioning of weapons began at midnight. It will run until May 2000.
Forensic tests cannot be carried out on any weapons that have been officially handed over and they cannot be produced as evidence in a criminal trial.
Those involved in the decommissioning process will also be exempt from charges of criminal possession.
Speaking at a press conference in Belfast yesterday, Gen de Chastelain said: "There is now no practical reason why decommissioning should not begin." He remained hopeful that weapons would eventually be destroyed, although none of the paramilitary groups has been willing to give them up so far.
The entire political process was littered with events that people had thought impossible, he said. While he did not think any paramilitary group was on the brink of handing over weapons, he thought decommissioning could take considerably less time than the two years laid out.
Gen de Chastelain said the two decommissioning schemes, established jointly by the British and Irish governments, would be "as simple as possible, as flexible as possible and as honourable as possible".
The decommissioning of weapons can proceed either by way of the provision of information to the Independent Commission, leading to the collection and destruction of arms by the body, or by verifiable destruction of arms by the paramilitaries themselves.
The paramilitary groups have agreed to certain individuals acting as go-betweens with the decommissioning body.
Mr Billy Hutchinson of the Progressive Unionist Party will be the UVF's representative. Pastor Kenny McClinton, a former loyalist paramilitary, will be the contact for the Loyalist Volunteer Force.
Gen de Chastelain said there had been no formal participation by the IRA or UDA so far. He added: "This is a voluntary event. Nobody is being defeated, nobody is engaging in surrender.
"It is an acceptance of the fact that the way forward is a democratic path, and there is no need for them in the future and, indeed, getting them out of the way reduces the temptation for somebody, for other purposes, to use them."
Regulations to provide for the decommissioning of paramilitary weapons came into effect in the Republic today, having been signed by the Minister for Justice yesterday.
The signing of the regulations, which gives effect to the Decommissioning Act, 1997, was in keeping with the Government's commitment under the Belfast Agreement to have schemes in force by the end of June.
The Minister of State at the Northern Ireland Office, Mr Adam Ingram, signed a similar order yesterday to give effect to the British Act.
The Belfast Agreement notes that the resolution of the decommissioning is "an indispensable part of the process of negotiation" and says that all participants "reaffirm their commitment to the total disarmament of all paramilitary organisations".
The document adds: "They also confirm their intention to continue to work constructively and in good faith with the independent commission, and to use any influence they may have, to achieve the decommissioning of all paramilitary arms within two years following endorsement in referendums North and South of the agreement and in the context of the implementation of the overall settlement."
The agreement said the independent commission would monitor progress on decommissioning, reporting regularly to both governments.