Criticism of Sinn Fein's reaction to the murders of two British soldiers in Antrim has highlighted the stark distinction which now exists in the republican psyche between the Army and the police.
Commentators have complained that the statement issued by the party president, Gerry Adams, was too little and too late, coming as it did 14 hours after the killings and with a tone described as cool and over-clinical.
The remarkable fact is that the peace process has reached the stage where Sinn Fein has formally signed up to support the policing and justice systems in Northern Ireland. Policing has undergone fundamental reform in recent years. As a result, mainstream republicans regularly declare that they accept and support the police force. They sit on the Policing Board which oversees it, urge Irish nationalists to join its ranks and tell their supporters to pass on information.
They regularly hold discussions with senior officers. Sinn Fein's Alex Maskey, for example, says of Chief Constable Sir Hugh Orde: "We have had many private discussions, often very challenging. I find him open enough – he gives as good as he gets."
But the British Army is different. To republicans it remains an "army of occupation" whose legitimacy they do not accept; much has changed in Northern Ireland, but this has not.
It is not just a matter of ideology, but also of violent experience: the Army killed 105 members of the IRA during the Troubles, while the IRA killed 447 regular soldiers.
This pro-police but anti-Army stance helps explain why the republicans took some hours to react to the Antrim killings. In a BBC interview yesterday, Mr Adams said he heard of the incident after 11pm on Sunday night after leaving a public meeting in Co Clare in the west of Ireland.
He said he watched Sky News until 1am, then after 6.30am consulted with a range of colleagues on the text of a statement which was issued at 11.30am.
The seriousness of the incident, which clearly has both security and political implications, together with his party's divergent attitudes towards the police and the Army, may help explain any delay.
These particular murders raised the issue of whether republicans should urge their supporters to assist police, whom they support, in tracking down the killers of the members of the Army, which they do not. This must have generated some debate.
In the end, the Adams statement used the formulation: "Sinn Fein has a responsibility to be consistent. The logic of this is that we support the police in the apprehension of those involved."
The striking thing is that the Sinn Fein response attracted so much criticism, but that it has not been attacked by the Democratic Unionist Party, who are their partners in government, by the British Government, or by the police.
All of these appear to take the view that Sinn Fein has to tread carefully in the republican underworld. The most immediately important of these elements is the DUP and its leader and First Minister, Peter Robinson.
The DUP has often in the past savaged Sinn Fein for approving of republican violence against the security forces, and it might have done so again. Instead Mr Robinson has focused on the Real IRA, who carried out the attack, and taken the line that this is not a time to seek party political advantage.
His stance has caused much relief in London and Dublin, since there were anxieties that the killings might lead to political recriminations, with consequent damage to the peace process.
The party had some difficulty in persuading its grassroots to support the police. It is considered beyond the realm of possibility within republicanism for them to go further and support the Army as well: nor would they want to.
In any event, Mr Adams and other Sinn Fein leaders have since gone much further than his original statement in various interviews. The Sinn Fein president agreed, for example, with one interviewer that the attack was "an attempt at mass murder".
Meanwhile Gerry Kelly, the minister who had a reputation as a fearsome IRA activist, called for information to be passed to the police, though he acknowledged that republicans had a historical aversion to doing so.
So far Sinn Fein and the DUP are demonstrating a convergence of interest: both recognise that the Real IRA would love to drive a wedge between them, but both are acting to preserve their joint administration.