It was a sad day for Northern Ireland yesterday when the Ulster Unionist Party walked out of the Executive.
Their bold move sends a clear signal that the IRA must be fully and permanently dismantled.
Republican paramilitaries understand pressure.
And yet, for all the failures of Stormont, there have been major successes too since 1998.
Republicans, while thoroughly dishonest about the past and while Syriza-like unreliable and unpredictable, have generally worked with the system.
IRA individuals have been involved in at least three murders but the Provisional command, which we are told still exists, has not pulled off a major operation since the Northern Bank robbery – a disgraceful act of criminality from a group that has political representatives at the heart of power.
Northern Ireland has in a sense needed a crisis to thrash out problems with the political structures here.
Sinn Fein may be a very different party to the mouthpiece for terrorists of 25 years ago, but its conduct over the Stormont House Agreement, agreeing to a degree of welfare reform and then suddenly backtracking (apparently in the interests of the southern party) was sheer political blackmail.
Its relentless, vindictive demand for full accountability over a past about which it is itself so dishonest is destabilising. But the biggest problem of all is a system in which parties must at all times be in government, regardless of what they do. There is in many respects no single government here. There are competing departments and parties tied together in an Executive that somehow manages to rumble along.
One thing must become clear during the Westminster parliament: a Conservative government must withstand SDLP and Dublin fury and contemplate specific sanction against Sinn Fein if its behaviour breaches governmental norms.
Meanwhile, Mike Nesbitt is right to imply that unionists have a role to play in getting society back on track, by taking down loyalist terror flags.