By Conor Humphries
BELFAST (Reuters) - When graffiti artists painted over a huge mural of Northern Ireland's soccer heroes with two armed men in balaclavas this summer, police in east Belfast took notice.
Within weeks the area had descended into its worst sectarian rioting in a decade, the latest stark reminder that 13 years of official peace has failed to remove political violence from Northern Ireland's streets.
Despite the success of a political marriage between once bitter Catholic and Protestant rivals in the local parliament, there are signs that radicals on each side are stepping up their use of violence to push divergent agendas.
"First came the murals and then the petrol bombs," said Arthur McDonald, 70, a Catholic whose estate was attacked by a mob, which police said was orchestrated by Protestant paramilitaries. "It's the only way they can get recognition."
Neither the street violence from disaffected Protestant loyalists, so-called for their loyalty to the British Crown, nor gun and bomb attacks by dissident Catholic Republicans, who want a united Ireland independent of Britain, are widespread enough to threaten the stability of the province.
But they are dashing hopes that the historic peace deal could end strife on the province's troubled housing estates.
Since 2006 the number of so-called "peace walls," diving Catholic and Protestant areas, has increased from 37 from 48, as the police try to dampen sectarian violence.
VIOLENCE 'ALWAYS WITH US'
"There seems to be a level of violence the political system does nothing to ameliorate or reduce," said Malachi O'Doherty, a writer and veteran political commentator. "It looks like it is something that will always be with us."
Elections in May were the most uncontentious in years, ushering in a second term of a power-sharing government between Catholics and Protestant parties. Sinn Fein, the political wing of the now-defunct Irish Republican Army, is now the junior partner to former arch rival, the Democratic Unionist Party.
The coalition was made possible by a 1998 peace deal that largely ended three decades of violence between nationalist paramilitaries fighting for a united Ireland, and mainly Protestant groups, who want to keep Northern Ireland British.
But fringes on both sides, too small to be represented in parliament, see the deal as a betrayal have responded by intensifying their use of violence.
Dissident Irish nationalists, who police say pose their biggest threat since the peace process began, killed a policeman in April for the first time in two years. Weeks later, nationalist gunmen in balaclava facemasks paraded in one of the most public displays of defiance in years.
In the riots in east Belfast, police said dissident republicans appeared to have fired shots, one of the most worrying elements of the clashes.
But police said the violence was planned and initiated by the Ulster Volunteer Force, a Protestant paramilitary group that has been largely passive for years.
The first sign that something was amiss on the Protestant Newtownards Road was when locals woke up to a 6 meter (20-foot) high mural of two UVF gunmen with a slogan proclaiming "the right, if you are attacked, to defend yourself."
It was the first time in at least five years that a new paramilitary mural, a crude barometer of sectarian tensions in the city, had appeared.
"People feel as though they are being left behind," said Jim Wilson, a 58-year-old former prisoner who has for years replaced violent murals with paintings celebrating peace. "I'm not annoyed by it, I understand that people feel frustrated."
Like many in his working class area, he feels Catholic communities, supported by the finely tuned political machine of Sinn Fein, have secured far more benefit from the peace deal than their Protestant neighbors.
Former paramilitaries have also been angered by what they see as bias against Protestants by the Historical Enquiries Team, set up by the police to investigate paramilitary atrocities.
"Some of the young paramilitaries feel they have to show who is boss," said Reg Empey, a unionist politician from the constituency. "They feel the cards are stacked against them."
The two communities, separated in places by a 20-foot peace wall, have joint programs to help children integrate. But underlying tensions are as high as ever. Men are regularly beaten up for having the wrong accent or football shirt.
"I am beginning to wonder if things are moving backwards rather than forwards," said Maggie Hutton, 38, a Protestant in east Belfast who sees the UVF as the only group capable of protecting her community from Catholic gangs.
While Catholic and Protestant groups are both increasing activity, leading to the worst summer of violence in five years, they are in effect waging two separate wars, said Neil Jarman, director of the Institute for Conflict Research.
"They are on two quite different trajectories," he said.
Small cells of Catholics paramilitaries focus bomb and gun attacks on the security forces, whom they say are occupying their country. They largely leave local politics to Sinn Fein.
Loyalists, on the other hand, many of whom feel alienated from the more middle class DUP, have channeled their energies into street trouble like the riots that followed a police decision to take down Loyalist flags in Balyclare last month.
Caught in the middle are the police service, who despite reinventing selves as a mixed force, bear the brunt of unrest.
They were recently forced to start to replace their fleet of heavily armored land rovers, a symbol of the Northern Ireland's three decades of "troubles," despite hopes the 1998 peace deal would allow them to be retired.
But despite the setbacks, they say unrest is on a far smaller scale than during the troubles that saw hundreds of people killed each year in the 1970s and '80s.
"These incidents are serious, they are dangerous, but they are compartmentalized," said Assistant Chief Constable Alistair Finlay. "Northern Ireland is not awash with people fighting."
(Editing by Paul Taylor)