An Irish worker with the United Nations, Mr Marcel Grogan, would not have recognised the group of Albanian guerrillas who opened fire on his white UN vehicle on Tuesday, even if he had caught sight of them before they machine-gunned the four-wheel drive Toyota.
Mr Grogan, who worked for the UN Humanitarian Affairs office in Belgrade, was driving with a local translator in southern Serbia just after midday on Tuesday when his vehicle, clearly marked with UN plates, came under fire outside the town of Bujanovac, five miles short of the Kosovan boundary with Serbia.
Mr Grogan took two high-velocity rounds in the legs. Then, much to his surprise, say UN staff in the Kosovan regional capital Pristina, his uniformed Albanian attackers appeared at the side of the road and apologised for having shot him.
He is now recovering in the huge US military facility at Camp Bondsteel in eastern Kosovo, after being evacuated by helicopter from a US boundary checkpoint on the Kosovo-Serbia demarcation line.
Without knowing it, he was one of the first international workers in the former Yugoslavia to have met the latest guerilla group thrown up by the Kosovo conflict.
"Who are the UCMPB?" reads the headline in the leading Kosovan newspaper, Koha Ditore, earlier this week.
The answer is a small, hardline gang of former Kosovo Liberation Army fighters who have sprung up in the mountainous terrain of eastern Kosovo and southern Serbia. Their aim is to protect their homes and villages from increasing attacks by Serbs.
The UCMPB translates as "Liberation Army for Medujeva, Preshevo and Bujanovac", and is predominantly drawn from three Albanian communities in southern Serbia, whose 70,000-strong ethnic Albanian population finds itself the target of a new round of harassment, attacks and forced displacement by Serb special police.
The area lies on the edge of the boundary with Kosovo, and the heartland of the UCMPB is the oak woods and muddy hills of the Presevo valley running alongside it. A group of 30 lightly-armed fighters currently control the village of Dobrecin, lying 700 metres inside Serbia, across the boundary from a NATO outpost operated by soldiers from the First US Infantry Division.
Half of the 2,500-strong population of Dobrecin fled to Kosovo last summer when NATO entered the province, and the rest followed in January this year, after Serb policemen shot dead two Albanian brothers collecting firewood just outside the village. The UCMPB was formed as a reaction to this incident.
Serb units of special police are just two miles up the road, at a roadblock just outside the town of Bujanovac. For them, the armed Albanian rebel presence just 4,000 metres away is like a red rag to a bull and NATO fears that the tiny village of Dobrecin, clearly visible from the US watchtowers on the boundary, may come under attack any day.
Under the terms of the Military Technical Agreement signed in June last year between NATO and the Belgrade administration of President Slobodan Milosevic, Dobrecin lies within a 5 km security buffer zone where only local Serb police are allowed to operate.
One US official with NATO said this week that NATO would intervene in the area in the event of an "atrocity" but in Pristina a NATO spokesman, Col Henning Philip, refused to speculate on what might constitute such an act.
One Serb special policeman was killed and three injured last weekend in an attack by the UCMPB near the village of Konculj, which lies seven miles north of Dobrecin. An Albanian fighter was also killed. The only thing certain for the Balkans' newest rebel group is that reprisals cannot be far away and NATO might not be so keen to intervene as the guerrillas might think.
The NATO-led peacekeeping force in Kosovo vowed yesterday to do everything in its power to prevent any "export of violence" to a tense neighbouring area in southern Serbia.
Kfor, expressing concern about the shooting of the Irish UN employee on Tuesday, said it would "not allow the territory of Kosovo to be used to support any activity aimed at using force and inciting tensions" in the region east of the province. This part of Serbia has a large ethnic Albanian population and has seen several violent incidents over the past few months.
Western diplomats and politicians have accused President Milosevic of reinforcing troops in the region east of Kosovo to spread fear and drive out ethnic Albanians. Belgrade says it is responding to "terrorism" by ethnic Albanian guerrillas infiltrating from Kosovo. Kfor said Tuesday's shooting confirmed that there were people in the boundary region with Kosovo prepared to use force to achieve their aims.