Gordon Brown yesterday welcomed the latest decommissioning moves of paramilitary groups in Northern Ireland and urged politicians to get behind the policing and justice deal hammered out last week.
In a Commons statement, the Prime Minister announced that the last loyalist paramilitary organisation to hold arms, the South-East Antrim UDA, had this afternoon "just completed their decommissioning".
It follows earlier confirmation that the so-called Official IRA, a relatively small organisation most active in the 1970s, had destroyed its guns.
Its declaration came only two hours after a separate republican splinter group, the Irish National Liberation Army (INLA), confirmed it had disarmed.
Mr Brown said this was a "central part of moving Northern Ireland from violence to peace".
He hailed the policing and justice deal as a "significant and defining moment" and said responsibility for making it work fell on all politicians.
Tory leader David Cameron offered his full support for the devolution deal and congratulated the Prime Minister for the part he had played in achieving it.
In a statement, Mr Brown said that, without the agreement, the "whole process of devolution and the peace process itself would be at risk".
He added: "This agreement is essential to securing the future because in turn it will also bring stability, investment and jobs."
Conflicts over institutions had dominated politics for decades in Northern Ireland.
"When the cross community vote takes place on March 9, and the parties request the transfer of powers, Northern Ireland's politicians will have, by April 12, full control over their government and be able to focus on the economy, jobs, housing, public services and policing and justice.
"With this agreement communities once locked in the most bitter of struggles are choosing to be bound together in a shared future with a common destiny."
Mr Brown said none of this could have been achieved without the Irish government and thanked previous prime ministers Tony Blair and John Major for their part in bringing the agreement about.
Mr Brown said talks leading up to the deal had been demanding because they went to the "very core of Northern Ireland's shared future".