Police have said a bomb that exploded on a country road in south Armagh was designed to kill or injure officers.
A device exploded at about 1730 BST on Saturday between Belleeks and Cullyhanna, blowing a crater in the road and damaging a stone bridge.
No-one was hurt in the incident, which politicians are blaming on dissident republicans.
Chief Superintendent Alisdair Robinson said police were treating the blast "extremely seriously".
They have launched a major investigation and are appealing for anyone with information to come forward.
Ch Supt Robinson said the bomb was "a totally reckless act that could have easily led to loss of life if anyone had been driving past at the time".
"However, I believe at this stage - the real target was my officers. This was an attempt to lure police into the area to injure or kill them," he said.
"At this stage we do not believe this incident poses any further risk to members of the public, but it does pose a significant risk to my officers. That is why we are treating this incident with extreme caution.
"The reality is there are people out there who have a callous disregard for the lives of both local members of the community and my officers. They took the decision to plant this device knowing only too well the potential deadly consequences."
The explosion happened about three miles outside the village of Belleeks, under a bridge on Carrickrovaddy Road, and police say surrounding routes will be closed for some time.
Sinn Fein MP Conor Murphy said it had created a "huge inconvenience" for people living in the area.
"The sole outcome of this attack is that the Creamery Bridge has been destroyed and the road has been closed," he said.
"One would also have to take into consideration the fact that this bomb could have seriously injured local people travelling on this road, a fact which the perpetrators seem to have ignored."
Ulster Unionist assembly member Danny Kennedy said he had "no doubt it was an attempt to raise tensions in the area before the Twelfth of July".
"I find the rise in the number of dissident attacks extremely worrying," he said.
"Actions like these have no place in our society and I urge anyone who has information that might help the police to contact the PSNI."
SDLP assembly member Dominic Bradley added: "Whatever the reason for it and whoever's responsible for it, it's wrong and shouldn't be happening."