ZENICA, BOSNIA-HERZEGOVINA — THE British officer's heart pounded and he cocked his 9-mm Browning when mujahideen fighters surrounded his nearby vehicle.
The soldiers inside bolted the doors and waited nervously for their officer to return as the curious Muslim Holy Warriors began to take interest in the Union Jack on the front panel of the car.
This particular group soon wandered off, and the tension dissipated. But fears of militants from Islamic nations are so high in central Bosnia that once-routine incidents are handled with great caution.
The NATO forces descending on Muslim-run Bosnia could become targets for hundreds of mujahideen here, who seek to prevent Western corruption of Islam. Yet the threat may be more "800 guys with nothing to do," as one British aid worker puts it.
"The problem is that they were on the front line, but there is no front line anymore," said Capt. Colin Armstrong-Bell, a British military spokesman.
Military troubleshooters still say Americans could be drawn into a "conflict" like the British forces, through no deliberate fault of their own.
During nearly four years of war in Bosnia, small units of fundamentalist Muslim fighters hardly presented a threat to British soldiers, to United Nations troops, or to any Westerner.
They come from Iran, Pakistan, Turkey, and other Islamic countries. They were all front-line volunteers with the Bosnian Army after tours in Afghanistan and elsewhere, serving what they saw as the "right hand" of God in what they deemed the new jihad.
But that was before a British UN soldier shot dead a Bosnian mujahideen, Muslim Elvedin Hodzic, in self-defense two months ago, sparking a spate of incidents that have left British soldiers anxious and relief workers fearful targets.
The Balkan peace agreement signed in Dayton, Ohio, last month expressly forbids the presence of mercenaries and "freedom fighters" of any kind in Bosnia, but the mujahideen here act with impunity.
Forcing women to wear veils and ridding towns of alcohol, they spread fear as much among moderate Muslims - the majority of Bosnians - as they do foreigners.
The murder of an American UN civil affairs officer on Nov. 18, at the town of Banovici, is believed by some to be linked to the mujahideen. Banovici is not far from where the US forces will be based in Tuzla, and American and NATO officials have expressed concern over the threat the extremist fighters pose to the Western troops.
The humanitarian cost has been high as well. The British Overseas Development Agency withdrew all its expatriate staff from Muslim government areas of Bosnia except Sarajevo for several weeks in November.
British officers believe that the mujahideen in Bosnia number roughly 800, two-thirds of them from abroad and the rest local. Some estimates put their troops strength at nearly 4,000. They are based at Podbrezje, north of the town of Zenica, but have proved difficult for the government - and regular Army - to control.
One group with long black beards races through Zenica in an old yellow Mercedes, with a green Islamic flag flying from a pole stuck out one window and a Bosnian government flag flying from another. The car is equipped with communications radios.
Showdown in Gornji Vakuf
The British relief worker was more direct about the shifting Holy Crusade: "They were looking for a fight, and it happened that a Brit killed one."
The first incident on Oct. 5 set the tone. During a patrol near Gornji Vakuf, a British soldier was set upon by a mujahideen shouting anti-British and anti-UN slogans.
The fighter pulled his gun, aimed it at the soldier's head, and cocked it. The soldier shot him once, then again, killing him, when the mujahideen continued to threaten him.
Local Bosnian authorities accepted the findings of a British UN report, but word began filtering through that "family and friends wanted blood for blood," said Captain Armstrong-Bell.
A few days later, in what was seen by the UN as a clear act of revenge, a UN Military Observer vehicle was engaged with small arms and a rocket-propelled grenade.
Soldiers have been told not to travel except in convoy. In some places, British military vehicles were seen without Union Jack markings and with their license plates covered with tape.
Threats have also been made toward many of the 60 or so relief agencies in central Bosnia, though they are fed at least as much by rumor as by fact.
A radio station around Zenica fanned flames further by announcing that two more mujahideen have been killed by British soldiers - a complete fabrication, the British Army says.
"The most worrying factor," said the director of one British aid agency, "is that these people are a law unto themselves. No civil or military authority can control them. It's a big problem, especially for the Bosnian government."
Islamic charities give food and aid - along with veils for women and Korans. And the suffering of the war has rekindled dependence on Islam. "The mujahideen have an aura about them, and they go in to scare the opposition," said Captain Armstrong-Bell. "We're conscious of the threat, but there has always been a threat here."
It is a threat American forces, too, are likely to become used to.