Northern Ireland's police chief said he gets briefings virtually every day about plots to attack and kill his officers.
PSNI Chief Constable Simon Byrne said the ongoing threat from dissident republicans remains a "real worry". And he said the shooting of senior detective John Caldwell sent a "shockwave" through the PSNI.
Last year, the threat level in Northern Ireland was raised from substantial to severe, meaning an attack is highly likely.
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There have been a number of terrorist incidents targeting police officers since then, with the most serious being the gun attack on Detective Chief Inspector John Caldwell in February.
Mr Caldwell, who has led many of the PSNI's most high-profile investigations, was shot several times outside a sports complex in Omagh, Co Tyrone, when he was with his son after coaching a youth football match.
The so-called New IRA claimed responsibility for the shooting, with police investigating if the dissident republican group may have been assisted by gangsters.
Seven people have appeared in court charged with attempted murder. Mr Caldwell spent several weeks in intensive care after the shooting.
He was later discharged from hospital and made his first public appearance since the attack last month, when he attended a garden party at Hillsborough Castle as part of the visit of the King and Queen to Northern Ireland.
In an interview, Mr Byrne said police are determined to keep the pressure on those intent on attacking officers.
He said: "Our biggest threat is those dissident republicans that want to kill and injure police officers.
"At the moment I am receiving virtually daily briefings about plots and plans to hurt police officers and to kill them. It is a real worry."
The chief constable added: "The threat from terrorists is severe, which means they have the capability to do it and an attack is highly likely.
"We have to adjust how we gather information, intelligence, the speed of our investigations, to make sure as best we can we are staying one step ahead of the terrorists.
"We are making arrests every week. We have obviously got a huge investigation running after the awful attack on our colleague John Caldwell.
"We need to keep the pressure up on a small number of people that are still intent on using violence to promote their ideology."
Speaking about the attack on Mr Caldwell, Mr Byrne said it was from an era everyone wanted to move on from.
He added: "Personally, it was a huge shock.
"I can remember going in and out of Omagh police station a number of times in the immediate days after the attack on John and there was a quite surreal and numb feeling.
"Definitely a shockwave went through the organisation because it was a colleague, but also because you understood the awful circumstances of the attack and the effect it had on his family.
"The way the organisation rallied round and the speed of the investigation has been impressive."
Mr Byrne said any return to work for the senior detective will be a decision for Mr Caldwell and his family.
He added: "I think it is remarkable that he has made such a swift recovery and I pay tribute to the medical professionals that clearly were integral to saving his life along with members of the public who gave him first aid.
"It was such an awful experience for him which will remain part of his future for the rest of his life."
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