Britain has put 600 troops on standby to deploy to Kosovo at short notice in case of violence following its planned breakaway from Serbia.
The Welsh Guards recently completed a tour of duty in Bosnia
The quick reaction force, formed by members of the 1st Battalion Welsh Guards, would be sent in an emergency.
The MoD says the force is part of the UK's commitment to Nato-led peacekeeping in the Balkans.
Currently, 200 British forces are serving in Kosovo, out of a total of 15,000 troops in the breakaway region.
Kosovo has been under United Nations administration since 1999 and is poised to declare independence from Serbia on Sunday following a protracted and bloody conflict between ethnic Serbs and Albanians stretching back centuries.
Should violence erupt again in the near future, the responsibility for providing back-up will fall to the UK.
Nato operates a rotating response force, with one member state setting aside troops every six months. The UK took over this responsibility on 1 January.
A spokesman at the MoD said the troops had been earmarked "in case Nato requires a force with extra flexibility to deter or combat outbreaks of violence."
The soldiers will be backed up by equipment including troop carriers and other armoured vehicles.
The Welsh Guards battalion is based at St Athan in the Vale of Glamorgan, south Wales.
Recent overseas tours have included Bosnia and Northern Ireland.
On Friday, the European Union approved the launch of a police and justice mission to help enforce the rule of law in Kosovo.
Two thousand police officers, judges and prosecutors will start deploying to Kosovo from next week in one of the biggest deployments of its kind by the EU.
Britain is sending around 60 police officers and judicial experts, although Germany and Italy are the biggest contributors.
All EU members except for Malta will take part, as well as five non-EU countries: Croatia, Norway, Switzerland, Turkey and the United States.