Defence Secretary Philip Hammond has warned that the Taliban is still a "potent force" in Afghanistan that should not be underestimated.
He said some 15-20 patrol bases had already been handed over to the Afghan National Army, which is becoming more self-sufficient all the time.
But he also said he is optimistic that momentum is building for a process of negotiation between the Afghan government and Taliban.
ITV News' International Correspondent John Irvine spoke to him in Helmand Province:
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Andreea Cristea, 29, remains in a critical condition after being rescued from the Thames after a terror attack along Westminster Bridge.
The Prime Minister has praised the former soldier's "huge professionalism" in trying to save the life of Pc Keith Palmer.
The man who carried out the Westminster attack is thought to be British born and was once investigated by MI5, the Prime Minister has said.