A breakaway republican armed group known as Oglaigh na hEireann has been linked to a surprise car bomb attack which injured a member of the PSNI police on Monday night.
Monday night's attack was the first time in six years that militant republicans have used a booby-trap device against the British Crown forces.
The 'Oglaigh na hEireann' -- using the traditional Irish language name for the Irish Republican Army -- is also understood to have been behind a series of bomb hoaxes in Cookstown, County Tyrone last weekend.
Local Ulster Unionist assembly member Derek Hussey said the attack in Castlederg, County Tyrone, suggested a "degree of targeting intelligence".
But the technical capacity of the group to construct and deploy the mercury-tilt switch device has caused the greatest surprise.
Although it was referred to by the International Monitoring Commission last week as a threat to the peace process, there had been little suggestion that the group was capable of mounting Monday's potentially fatal attack.
The northwest area, including west Derry and Tyrone, has emerged as a relative stronghold for republican hardliners.
Two other attacks have taken place in the area on PSNI members in recent months. These were attributed to the Real IRA, which broke from the Provisional IRA in 1997.
The group responsible for Monday's attack is understood to have formed following a local split with the Continuity IRA, which has been in existence since 1986.
It is also believed to have been behind the murder of Strabane man Andrew Burns, killed as an alleged informer.
On Thursday, the Real IRA left a hoax device on the Belfast to Dublin rail link at Poyntzpass in County Armagh, causing disruption to the cross-border service. The style of attack has been used in the past to draw in and engage with British troops.
The alert was timed to coincide with a high-profile US international investment conference which was taking place in Belfast on the same day.
PSNI Chief Hugh Orde claimed this week that the republican armed groups "know they are in their endgame" and are "desperately lashing out".
"They have not defeated the police service for the last 38 years, if they seriously think this sort of event will defeat the Police Service of Northern Ireland they are badly mistaken."
Sinn Féin's Martin McGuinness, who is Deputy First Minister in the Six-County Executive, described the attack as "spiteful, selfish and futile".
"It was conducted by people who have no mandate. They certainly have no strategy whatsoever and clearly they represent no-one.
"There is a duty, a responsibility on everyone within society and indeed anyone who has information about this particular attack, to give the information to the police as quickly as possible."
The Mid Ulster MP said there was a possibility militants could strike again but he insisted they would not undermine the political institutions.
"Within recent months they have actually described me as a legitimate target," the Mid Ulster MP said.
"We are not going to bow to them or anyone else, we are going to continue to represent people."
British Direct Ruler Shaun Woodward yesterday proscribed [outlawed] the Oglaigh na hEireann group, making membership an offence punishable by imprisonment.