Most Britons know too little about Northern Ireland's politics to fathom why a murder could bring the arrangement that has kept the peace, in the words of one of its most senior politicians, to the "brink" of collapse.
The murdered man
Kevin McGuigan, 53, was shot dead outside home in east Belfast by men wearing black masks and carrying automatic weapons. Within hours, claims he had been killed by the IRA, of which he had been a member, were fuelling speculation it could threaten the fragile power sharing agreement at the province's devolved Stormont parliament.
This power sharing set up has brought relative peace to a place where people were shot and blown up for decades as the paramilitary IRA fought the police, the army and Unionist paramilitaries over the whether the province should be British or Irish.
Kevin McGuigan, pictured in hospital in 2011 with his grandson Ollie
It disarmed and supposedly disbanded after the 1998 Good Friday Agreement that reshaped Northern Irish politics and brought both sides into government together.
But Northern Ireland never had its Peace and Reconciliation Commission. Its historic divisions persist and animate so much of its politics.
Why the existence of the IRA is key
When police chief George Hamilton said he believed IRA members had killed Mr McGuigan and that its structure remains "broadly in place", it led to the Democratic Unionist Party (DUP), the largest in Stormont, denouncing Sinn Fein, the political party that was closely linked to the IRA and Northern Ireland's largest Nationalist party.
Sinn Fein denied the IRA still existed. The Ulster Unionist Party (UUP), the smaller rival to the DUP, said it would withdraw from the executive as Sinn Fein's claim made them "impossible to do business with".
Kevin McGuigan's funeral, his coffin draped in the flag of the Irish Republic, with which Nationalists closely identify
Yesterday, First Minister Peter Robinson and most of his party colleagues on the executive announced they would resign. He said the continued existence of the IRA had pushed the government "to the brink". Crisis talks between the parties continue. A poll, carried out after May's general election, found only 45% of people believed peace was durable.
The British government has the option to suspend devolved government and govern by direct rule. Dr Paul Dixon, an expert in Northern Ireland's peace process, said he believed the British government would do "everything it possibly could" to avoid this.
Why Westminster is unlikely to intervene
Because the general public regard Northern Ireland as "solved", there is little for a British prime minister to achieve in increasing Westminster's involvement there and doing so would be an "anathema" to David Cameron, Dr Dixon added. Whitehall and Westminster have sought for decades to be less involved in Northern Ireland, even when the British Army was there in force, he said.
The Kingston University London academic told The Huffington Post UK that reverting to direct rule could inflame tensions and fuel divisions by ending the "compromise" offered by power sharing in a devolved Northern Irish government, the loss of which jeopardises the peace process "big time".
The crisis exposes deeper problems
Dr Dixon called power sharing "a sticking plaster, not ideal". "You want the situation to heal more but the sticking plaster means we've not had lots of bleeding and war."
Peter Robinson (left) with Sinn Fein's Martin McGuinness
While politicians like Mr Robinson and Sinn Fein's Martin McGuinness represent the respectable faces of Unionism and Nationalism, both have hardline elements, which often look and behave like paramilitaries, who resent what has happened in the era of power sharing.
"It's those kind of marginalised elements that might come a bit more to the fore in a situation where there isn't this devolution of power," Dr Dixon said.
"There are people there who think 'well, we wouldn't mind going back to war and this time we might win it'. Fortunately, the political community has been pretty much united in marginalising those people but they can't ignore them.
"Republicans will be going, we've just got Brit rule from London, what's in it for us?' That's not good."
The prime minister spoke with Mr Robinson this week and told him he would not suspend Stormont despite "the gravity of the situation".
“They discussed options for what more the UK Government could do to comprehensively address all remaining paramilitary activity in Northern Ireland," a Downing Street spokesman said on Thursday, adding Mr Cameron "underlined the need for intensive cross party talks to identify ways to tackle all paramilitary groups" but called for "a return to the spirit that had seen politicians show such leadership over the years to deliver a peace process that has inspired people across the world."
Solutions to the crisis...
Northern Ireland is far more peaceful now than the height violent days of The Troubles but the level of violence had always been on a shifting spectrum, rather than a case of outright peace or war.
Dr Dixon added: "Although it's much power towards peace than it ever was, if you follow the news closely, you still see, people trying to plant bombs, trying to kill people, still antagonism over flags... The problem with the periodic coverage is everyone thinks 'oh, it's sorted and it's solved'. Then someone gets killed and all the cameras come back and everyone goes 'oh my god, I thought we'd solved this.'
He said the DUP's hard reaction to the supposed revelation that the IRA still exists was done for fear of being "outflanked on outrage" by the UUP and other Unionists, describing their strategy as a "'throw your toys out of the pram" exercise.
"[You] demonstrate to your electorate that you're outraged at the IRA's existence, although, if you've any sense, privately, you would have known they they continue to exist... In negotiations try and create a situation where everyone gets a win and you're able to go back to power sharing with everyone getting prizes."
Succeeding in doing this will not be easy, as Northern Ireland is still seen as zero sum game in which one side can only gain at the other's expense, he added.
"You have to choreograph the situation so that everyone appears to be winning to return to devolution looking good," he said.
"That's a tricky problem in Northern Ireland."