1. 9. Negotiations

2. Israel and the PLO Oslo Accords 1993
Israeli PM Yitzhak Rabin and PLO Chairman Yasr Arafat at the White House 1993
Ultimately, many nations, particularly democracies, decide to negotiate. This is more likely to happen when the terrorist group is an ethno-nationalist group. There are theories about when and why this happens:
Exhaustion: some argue that after about 30 years everyone has had it. They reach a point of being tired of the war and a new generation of leaders looks at a lifetime of fighting and it doesn’t seem to make much sense any more. They are ready to actually talk to their enemies.
Funding: Some argue that an ethno-nationalist group will begin to negotiate when its funding starts to dry up. The PLO got serious about negotiations when the USSR decide to stop funding the PLO. The PLO then aid to Israel, let’s talk. The result was the Oslo Accords, which took the two sides about 90% of the way to peace. But some of the details (Jerusalem, Israeli settlements among them), scuttled the deal and the crisis continues.

3. Rejection of Accords by Hamas
One of the reasons the crisis continues is the problem of spoilers or rejectionists. Even if the PLO and Israel had resolved all their differences, Hamas – a more radical Palestinian terrorist group – rejected the Oslo Accords and tried to restart the violence between Israel and the Palestinians by launching waves of terrorist attacks against Israel. It worked to ramp up the violence and make peace much more difficult. We’re 21 years past the Oslo Accords now and stil the fighting continues.

4. UK and IRA Belfast (Good Friday) Agreement (1998)
British prime minister Tony Blair and taoiseach Bertie Ahern signing the Belfast Agreement in April, 1998
The IRA and the British government signed an agreement to end the struggle over Northern Ireland in In the big picture, the British decided that making concessions was better than continuing the fighting to another generation. The IRA leadership agreed. The core of it was deciding what issues will be the authority of the UK parliament and what issues will the authority of the Northern Ireland Assembly. Power over local issues was devolved to the Northern Ireland Assembly. Also the Assembly operates with special rules in some areas. Issues like the budget for example have to be passed with a majority among the nationalist groups (who leaned toward the IRA or were IRA) and unionist groups (who leaned toward the UK). As a result of that procedure, on key issues no group can out vote the other one by simple majority rule. This might not work if the nationalists could win a simple majority and pass legislation that hurt the unionists badly. And vice versa. Then the violence might begin again. The agreement has its critics (most non-violent) and working out the power sharing agreement in Northern Ireland has been difficult, there is peace. Just about everyone agrees that making arguments on the floor of the Assembly is better than killing each other in the streets. But it took them about 25 to 30 years to decide that.

5. Rejection of Accords by Real IRA
15 August 1998, car bomb by Real IRA, Omagh, County Tyrone, 29 dead; from BBC News:
But not everyone in the IRA agreed. Two new groups split out of the IRA by those who rejected the Belfast Accords. The Real IRA and the Continuity IRA. Here is one way the Real IRA responded to the accords.