British and other Nato troops are to launch an offensive to take back areas of southern Afghanistan.
Major General Nick Carter, the British general in charge of forces there, told the BBC that the operation would "assert the control" of the Afghan government in parts of Helmand province now controlled by the Taliban.
He told Radio 4's The World At One: "Helmand is very much a work in progress, with parts simply ungoverned. If they're governed at all, it's by parallel governments provided often by the Taliban.
"If we're going to win the argument on behalf of the Afghan government... then we need to assert the government's control over those areas which are at the moment ungoverned."
He declined to say when the joint Nato/Afghan army operation would begin.
It is expected to include parts of central Helmand which have not been under Afghan government control for months, or in some cases years.
He said there are signs that Afghans in the area are taking a greater role in operations.
"(There has been) a transition, about the Afghans taking 'ownership of the responsibility'.
"What I've been very struck about... is the way the provincial governor, Governor Mangal, and the Afghan army and Afghan police wish to take ownership of this problem. And when they do, there is an Afghan answer to the problem. Afghans are standing up and being counted and that makes a big difference to what happens on the ground."
He added: "What's really important... is that if there is a conversation before the operation between the Afghans and the maliks, or the village leaders, on the ground, and it is explained to them what will happen when the government asserts control and authority over those areas, we often find the Afghans don't fight - but they will welcome you."