Dissident republicans are continuing to target police officers, despite the widespread condemnation of the murder of Ronan Kerr last weekend.
Constable Kerr was killed by a bomb under his car outside his Omagh home.
Police sources have said the community response and appeals to dissidents to end their violence have had no impact.
A source said intelligence information suggested dissidents have continued to target officers since Mr Kerr was killed on Saturday.
"There is nothing to suggest a lessening of operational tempo, there has been no diminution of activity," the source said.
Mr Kerr's funeral witnessed unprecedented scenes - with police officers and members of the Gaelic Athletic Association uniting in his memory, as well as politicians from across all the main Northern Ireland parties.
Many of those who attended expressed the hope that the level of public outrage would make dissident republicans think again. But it would appear it has not.
The police source said there was no indication that the strong condemnation of the murder, or the community response to it, has had any impact on dissident republicans.
It has also been revealed that the police have set up a special team of detectives to investigate the past in an attempt to prevent future attacks.
They will use new forensic techniques to re-examine evidence gathered at the scenes of terrorist attacks going back around 20 years.
The team started work last Friday, the day before Ronan Kerr was killed.
Its task is to try to find evidence to link individuals suspected of involvement in ongoing dissident republican activity to previous unsolved murders and bomb attacks.
Detectives will also investigate the financial affairs of suspects in the hope of finding evidence of criminal activity.
In terms of the present, the police expect dissidents to attempt to step up their activities in the run up to the assembly elections and the Queen's visit to the Republic next month.
The PSNI will be stepping up its overt - and covert - activities to combat the increased threat level.