US President Barack Obama said US and NATO-led troops had pushed back the Taliban in Afghanistan but he warned that there was still a long, hard campaign ahead.
"We knew that this summer was going to be tough fighting, that there was an interest in the Taliban exerting control. They have, I think, been pushed back but we still have a long way to go. We've got to get through elections.
"We've got a serious fight on our hands and we've got to deal with it smartly but we've got to deal with it effectively," Obama said in an interview with Britain's Sky News on Saturday during his visit to Ghana.
Fifteen British soldiers have been killed this month in southern Afghanistan, where US and British forces are battling Taliban insurgents ahead of the presidential and provincial council elections on August 20.
The surge in casualties has raised the British death toll in Afghanistan above the number of dead in the Iraq campaign and raised questions in Britain about tactics and strategy.
Obama said the contribution of the British military was "critical" and establishing peace and stability in Afghanistan was essential to prevent it again becoming a launch pad for terror attacks on the West.
"This is not an American mission. The mission in Afghanistan is one that the Europeans have as much, if not more, of a stake in than we do... The likelihood of a terrorist attack in London is at least as high, if not higher, than it is in the United States.
"And that's the reason why (former and current British prime ministers) Tony Blair and Gordon Brown and others have made this commitment."
Obama said he wanted a new push after the election to train Afghanistan's army and police so Afghans could take greater responsibility for controlling their own security.
"I think we need to start directing our attention to how do we create an Afghan army, an Afghan police, how do we work with the Pakistanis effectively, so that they are the ones who are really at the forefront at controlling their own countries.
"All of us are going to have to do an evaluation after the Afghan election to see what more we can do.
"It may not be on the military side, it might be on the development side providing Afghan farmers alternatives to poppy crops, making sure that we are effectively training a judiciary system and a rule of law in Afghanistan that people trust." Brown defended Britain's strategy for Afghanistan on Saturday, saying it was "the right one" and he insisted the western allies were winning the battle against Taliban insurgents in their heartlands of Helmand Province.
The prime minister said it was vital that the country not become an "incubator for terrorism" where the Taliban could provide a safe haven for Al-Qaeda.
Fatalities have risen since British forces launched Operation Panther's Claw, an assault on the Taliban in Helmand Province, which is designed to create safe conditions for Afghans to vote in next month's elections.
The Afghan interior ministry said Sunday that British and Afghan troops had killed up to 200 insurgents in the operation.
The United States has said it is sending up to 30,000 new troops to Afghanistan this year as the Taliban -- ousted from power by the US-led invasion in 2001 -- has regrouped.
Thousands of the additional US troops have been deployed in Helmand, where most British troops are based.
But defence minister Bob Ainsworth rejected angrily to accusations from a British political rival that British troops had been "bailed out" by the US forces.
"This is not an American takeover, I think it is quite disgraceful for people to suggest," he told Sky News.
British forces organised "coordinated operations" with the US forces as soon as they arrived in Helmand, Ainsworth said, and troops were working as a coalition.