Brown: We will continue to adapt and improve our counter insurgency strategy
Prime Minister Gordon Brown has said the UK's aims in Afghanistan are "realistic and achievable" in a speech defending the government's strategy.
He said he knew he was asking "a great deal" of British troops, more than 50 of whom had been killed this summer.
But he said he believed they were doing the "right thing" by Britain and for the people of Afghanistan.
On Thursday ministerial aide Eric Joyce quit, questioning the government's arguments for keeping troops there.
And on Friday the Ministry of Defence named Lance Corporal Richard Brandon as the soldier killed in an explosion in southern Afghanistan on Thursday.
The total number of British personnel killed in the country since 2001 is 212.
In a long and detailed assessment of Britain's strategy at the International Institute of Strategic Studies, Mr Brown attempted to set out what he believes are the measures of success for Britain in Afghanistan.
He said Taliban tactics had changed from a head-on military conflict to, effectively, guerrilla warfare using explosive devices - 1,000 of which had been dismantled this summer.
It remains my judgement that a safer Britain requires a safer Afghanistan
Other measures of success would be increasing Afghan forces and strong leadership in Afghan provinces as well as more economic progress, to give people a stake in the country, other than in heroin production.
Britain was committed to training up more Afghan forces, moving from a mentoring to partnering them, he said.
He was careful not to commit to a timetable for the withdrawal of British troops, but said: "It remains my judgement that a safer Britain requires a safer Afghanistan."
Downing Street has been keen to stress that the speech was not a response to Eric Joyce's resignation and had been planned for some time.
But Mr Brown said he wanted to tackle "head on" some of the criticisms of the government's strategy insisting that British troops are part of an international effort involving over 40 countries and that their presence in Afghanistan reduced the threat of terrorism on Britain's streets.
UK AND US OPINION ON WAR
In UK, 58% believe the war is not winnable, 31% disagree. ComRes/Independent. July 09
In US, 42% think America is winning the war, 36% think it is losing. ABC News/Washington Post. Aug 09
54 British troops killed in 2009 so far, compared with 47 in 2008
172 US troops killed in 2009 so far, compared with 155 in 2008
And he said there was "nothing more heartbreaking" than meeting the families of those killed, or those who had been seriously injured, in action.
He added: "When I meet young people who have suffered at the hands of the Taliban and who are in hospital and when I meet the families of those people who have been bereaved, I have to keep asking myself: 'Are we taking the right decisions for them and for the conduct of the action in Afghanistan?'
"Are we doing what is right both by our forces and by the population of this country? And every time I ask myself these questions, my answer is yes, we are taking the right action, the action that is necessary, to safeguard both our country and promote security in the world."
Mr Joyce told the BBC the government "must make it clear that there is an end in sight" to operations in Afghanistan.
He said: "I think it's important that we reflect on exactly why we're in Afghanistan.
"I said already, of course it's all about securing people in the UK, but it's also important to note that there are lots of other countries, just as big as Britain, that don't contribute in the way we do and also America are so vast they could do the job themselves."
There are more than 9,000 UK troops in Afghanistan and opposition parties have been questioning whether they are sufficiently equipped for the operation.
Mr Brown said in his speech that military spending had been increased, and was about £180,000 per year to support each soldier fighting in 2006 but was now over twice that, £390,000 for each soldier.
Shadow defence secretary Liam Fox said there was a "great deal of disquiet" on Labour benches.
"If we are to speed up the training of the Afghan National Army, how exactly will this be done? Will it require more British troops?
"On the equipment front, we need to see more armoured vehicles delivered more quickly and we need to know how they are going to be transported given the lack of airlift capacity. Much more detail is required about the practicalities on both manning and equipment."
Liberal Democrat leader Nick Clegg said: "Eric Joyce confirms what I have been saying for a long time, our approach in Afghanistan is over-ambitious and under-resourced."
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