As NATO defence ministers hold talks in Istanbul on their strategy in Afghanistan, UK forces have begun to pave the way for a major NATO assault.
Ministers have been told that British troops have launched helicopter advances in the southern Helmand province.
This to prepare the battlefield for a major operation against a Taliban stronghold.
Military sources say the assault will be one of the biggest of the eight-year-old war.
Taking part will be some of the 30,000 extra US troops sent to Afghanistan at the end of last year.
The operation is on the outskirts of the Nad Ali district, described as one of the last major Taliban-held bastions.
Afghan forces will also take part in the operation, with new efforts to boost their training.