British troops have established a permanent presence outside Helmand province for the first time since 2006 in an effort to secure a key road that runs through one of Kandahar's most violent districts, according to US and UK officials.
Since mid-December troops from the Household Cavalry have been operating on a 20km stretch of Highway One in Maiwand district where they are overseeing patrols and checkpoints
alongside soldiers from the Afghan National Army.
Maiwand is one of the last areas to be affected by the US troop surge. British troops were asked to oversee the western part of the district so that US troops could be deployed elsewhere in Kandahar province.
The UK's involvement in the province, which will continue for six months, has been kept quiet until now, in part because of sensitivities about British troops operating outside the area controlled by Task Force Helmand, the UK-led military mission in southern Afghanistan.
Although substantial numbers of British pilots and support staff are based at Kandahar Air Field and a portion of the UK force has at times acted as a roving air assault team across the south for years, since 2006 the vast majority of UK soldiers have been concentrated in Helmand and been under British command.
But after years of being the main international presence in what became known as 'Helmandshire', the UK's role has been reduced by a surge of thousands of US marines into the province and neighbouring Kandahar.
With so much UK blood and money spent in Helmand, British officials fought against American suggestions last year that UK forces should be entirely redeployed outside Helmand.
Instead the UK clung on to retaining full authority over just three districts: Nahr-e Saraj, Nad-e Ali and Laskar Gah.
Under the arrangement in Maiwand, which neighbours the area under UK control, British troops fall under the authority of US-led Regional Command South.
"No boundaries have been permanently changed and RC South will still maintain all governance and development responsibilities in Maiwand," a US Marine Corps spokesman said.
During a visit to Afghanistan this week the defence secretary, Liam Fox, insisted Britain was happy to operate outside Helmand and in a subordinate role.
"We want to be a good Nato partner and that's why we are on Route One at the moment," he said. "We don't see our bit of Helmand as being a unique British territory. We are here as part of Nato and people need to grasp that."
With Maiwand almost halfway between Helmand's regional capital of Lashkar Gah and Kandahar City, it also represents the final element of the much-delayed strategy, first drawn up more than a year ago, to clear insurgents from the critical road that links southern Afghanistan's two major cities.
The British are not taking on an easy task in Maiwand, which was one of the last remaining Taliban strongholds to be tackled by US marines.
Not only were the Taliban well entrenched in Maiwand, the district was the scene of one of the most disastrous confrontations between British troops and Asian forces in the 19th century when nearly 1,000 soldiers were killed at the Battle of Maiwand in 1880.
British and American officials, who refused to say how many troops were stationed in Maiwand, said that so far there had been few serious incidents or attacks by the Taliban.