Last night, Gary McMichael, leader of the Ulster Democratic Party, said he believed the IRA had returned to violence. "All the fingers are being pointed solely at the IRA and that being the case their ceasefire has ended," he said. His comments were given added weight by the arrest of three men, at least two of whom are believed to be suspected members of the IRA, in connection with the shooting.
At the same time, another republican group, the Irish National Liberation Army, denied responsibility for the shooting of Robert Dougan, the man killed yesterday as he sat at the wheel of his car.
He was said to be associated with the Ulster Defence Association, and had been the subject of two previous murder attempts. He was shot by a lone gunman outside the Balmoral Textiles factory in the south-western Belfast suburb of Dunmurry. A man in a baseball cap and two other men were seen running away from the scene.
The shooting will place extra pressure on the peace process, already in a delicate situation because of a growing row between Mo Mowlam, Secretary of State for Northern Ireland, and Ken Maginnis, security spokesman for the Ulster Unionist Party.
Her political development minister, Paul Murphy, said last night that if the latest killing was shown to have been committed "by an organisation connected with a participant in these talks, then the implications of that will need to be very seriously examined".
He added: "The Government is determined to maintain the integrity of this process."
While that comment will be seen as an implied threat to Sinn Fein, the Government knows if it throws it out of the Stormont talks there may be no process left. Equally if it lets the party stay knowing the IRA was behind the murder, the talks could well collapse.
As the security forces went on alert yesterday, the political climate was not eased by the worsening row between Ms Mowlam and Mr Maginnis. Ms Mowlam had stated that she would no longer talk to Mr Maginnis because of a series of "personal attacks" by him against her, unless he apologised.
The MP for Fermanagh and South Tyrone refused and stated that he was now "effectively barred from the talks". But with the situation worsening in the province the two agreed to put aside their differences at a meeting in a canteen in the House of Commons yesterday afternoon.
Last night, police arrested three men in the Catholic district of Twinbrook, near to the scene of the shooting and where the getaway car was abandoned. A detective, speaking on condition of anonymity, said that at least two of those being interrogated were considered IRA suspects.
Last month, the INLA shot another leading loyalist, Jim Guiney, as he worked behind the counter of his Dunmurry carpet shop. A friend of Mr Dougan who had been with him minutes before he was shot said: "He was very wary - he knew they were after him." He added that Mr Dougan had been very conscious of the security risk and had taken precautions at his home.
Mr Dougan was the second man to be shot dead in Belfast in 24 hours. On Monday night, a drug dealer, Brendan Campbell, was gunned down outside a restaurant. Royal Ulster Constabulary sources said the IRA, under the pseudonym of Direct Action Against Drugs, had shot and wounded Mr Campbell several weeks ago. A senior RUC officer yesterday described the situation as " incendiary".
Mark Fulton, a friend of the murdered Loyalist Volunteer Force boss Billy Wright, yesterday survived a murder attempt in Portadown, co Armagh. He blamed the UVF, from which the LVF broke away; this was dismissed by a UVF spokesman.