Terrorist attacks are part of normal life in Northern Ireland and should be expected during the G8 summit, the PSNI commander of the security operation has said.
Assistant Chief Constable Alistair Finlay said dissident republican attacks are part of the "normal backdrop" of life.
But he said he expects any incidents will take place away from the conference venue in Fermanagh and other key areas linked to the event.
Mr Finlay said: "I've got no reason to say that dissidents won't do something during that period of time. This is the normal backdrop. This has been the backdrop, the sad reality of Northern Ireland over quite a period of time.
"There is nothing to suggest that the rhythm of that will be disrupted. It would be great if it did, and maybe the policing operation, which is in part designed to do that, will prevent any of that happening during the G8. But we would say people shouldn't be surprised if there are incidents. We anticipate those incidents won't be at, near or affecting any part of the delivery of the G8."
The New IRA and ONH (Oglaigh na hEireann) are currently the most active dissident groups, he said, which have "real capacity and capability".
He added: "The period of G8 is an opportunity for those groups who want to feel they're noticed by threatening harm to communities and to my officers in their normal business. During that period of time the policing footprint around Northern Ireland will be large, there will be significant opportunities of detention, and those are features that the dissident terrorist doesn't particularly find attractive."
Mr Finlay said the 3,600 police from outside Northern Ireland that are being used here during the G8 will not be deployed in normal policing duties.
"They are going to be focusing on venue protection, route protection. They are going to focus on management of protests associated with G8. They are not going to be doing normal PSNI policing business," he said.
"We will also embed with each unit coming from Great Britain a number of PSNI officers, and those PSNI officers of course are routinely armed with personal protection weapons. They will provide local knowledge but also a degree of protection."
He does not believe officers from Britain are in any more danger than domestic officers.
"I've got nothing to suggest the dissidents see them as a target in particular. The kind of thing the dissidents target is us, the PSNI, the indigenous police officers.
"The preference is attacking police at their homes or other places with under-vehicle improvised explosive devices. Those are the most insidious and most destructive problems we've had."
The PSNI already frequently uses air cover and has brought forward the purchase of a new helicopter to coincide with G8.
The force has also ordered three drones which it is hoped can be used during the summit.
The G8 security operation, the biggest in the PSNI's history, will see 3,600 officers drafted in from forces across Great Britain, 2,500 of whom specialise in public order. Another 4,400 officers from PSNI are also due to take part. The Government has agreed to reveal the cost of security after the event. Officers coming from Britain have had to be trained in getting in and out of armoured Land Rovers and how to work around water cannon. They have been kitted out with ballistic body armour and will be accompanied by PSNI officers, who are routinely armed, while on patrol.