The increasingly deadly conflict in Afghanistan is a "serious fight" but one essential for the future stability of the country, the US president says.
Insisting that US and allied troops have pushed back the Taliban, Barack Obama said the immediate target was to steer Afghanistan through elections.
The country is due to hold a presidential vote in August.
Mr Obama spoke to Sky News as concern grew in the UK at the rising British death toll in Afghanistan.
UK Prime Minister Gordon Brown was also forced on Saturday to justify British involvement in Afghanistan.
Mr Brown said the UK’s military deployment there was aimed at preventing terrorism in the UK.
Fifteen British troops have died in the past 10 days, pushing the country’s number of deaths in Afghanistan past the number killed in action in Iraq.
‘Extraordinary role’
Speaking during a day-long visit to Africa, Mr Obama also told Sky News that the battle in Afghanistan was a vital element in the battle against terrorism.
He said the continued involvement of British troops in the conflict was necessary, right and was a vital contribution to UK national security.
"This is not an American mission," Mr Obama said.
"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."
He praised the efforts of all troops currently fighting the Taleban in gruelling summer heat, singling out British forces for praise when asked if their role was still important.
"Great Britain has played an extraordinary role in this coalition, understanding that we can not allow either Afghanistan or Pakistan to be a safe haven for al-Qaeda, those who with impunity blow up train stations in London or buildings in New York.
"We knew that this summer was going to be tough fighting. They [the Taliban] have, I think, been pushed back but we still have a long way to go. We’ve got to get through elections."
‘Core mission’
Since taking office in Washington in January of this year, Mr Obama has announced a troop "surge" in Afghanistan.
The US has said it is sending up to 30,000 new troops to Afghanistan this year to take on a resurgent Taleban. They will join 33,000 US and 32,000 other Nato troops already in the country.
He also replaced the incumbent US commander in the country, ousting Gen David McKiernan less than a year into his command.
The new US chief in Afghanistan, Gen Stanley McChrystal, has a stellar reputation from his days commanding special forces operations in Iraq.
He has been tasked with the mission of outsmarting the Taliban, who continue to win support among ordinary Afghans often caught in the crossfire of the bitter fighting.
High numbers of Afghan civilian casualties have become an issue of major concern to the US. Afghan President Hamid Karzai has regularly called on the international forces to reduce the numbers of Afghans killed in its operations.
Speaking to Sky News, Mr Obama said although forces were currently engaged in heavy fighting, new strategies for building bridges with Afghan society would be considered once the country had held its presidential election.
Afghanistan needed its own army, its own police and the ability to control its own security, Mr Obama said – a strategy currently being implemented in Iraq, where security is being handed over to Iraqi forces.
"All of us are going to have to do an evaluation after the Afghan election to see what more we can do," the president said.
"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."
"We’ve got a core mission that we have to accomplish."</p
This article is from the BBC News website. © British Broadcasting Corporation, The BBC is not responsible for the content of external internet sites.
I apologise for Berlusconi
I’m sorry for our prime minister’s predictable reaction to a story about G8 summit preparations, please keep the spotlight on Italy
As a member of the Italian parliament and former magistrate who ensured that many corrupt politicians and businessmen were brought to justice in the 1990s, I wish to apologise to the editor and staff of the Guardian newspaper for the utterly predictable reaction of prime minister Silvio Berlusconi and our foreign minister, Franco Frattini.
The Guardian does its best to keep the public informed. In Italy this government is not accustomed to free debate, or to hearing the truth being told. While sections of the article dealing with preparations for the G8 summit may be debatable, the rest of it contains little that can be refuted.
However, there is one classification missing from the list in the article, one published by Freedom House, which puts Italy 73rd place for freedom of the press. The real problem in our country is that information is firmly in the grip of one individual, namely our prime minister, Silvio Berlusconi – which must be one of the worst cases of conflict of interest ever recorded in any country in the western world.
Berlusconi’s control over the media is exercised via his ownership of the largest Italian publishing house, Mondadori, as well as via the country’s six television networks: three private Mediaset channels owned by Berlusconi himself and three channels of the public broadcaster RAI which Berlusconi indirectly controls and influences, with very rare exceptions I might add, through managerial staff appointments.
His virtually total control of the media allows him to maintain a dominant position and provides an endless source of revenue that helps to consolidate his position within the institutions via a wide-ranging system of patronage. In the past, these revenues were made possible by the tacit approval of previous governments that refused to address the issue of obvious conflicts of interest. Currently Berlusconi pays the Italian government a mere 1% of turnover in return for the television broadcasting frequencies conceded to him and now used for Mediaset transmissions. Since the centre-right coalition government came to power, a number of major parastatal companies have diverted their advertising expenditure from the RAI public television networks to the private networks belonging to the prime minister.
In addition to the media issue, there is now also another, namely the scourge of the “unconstitutional” government reforms. The first of these was a law known as the Alfano bill, which was ordered by Silvio Berlusconi himself as his first act after coming to power, which prohibits the prosecution of himself and the incumbents in three other senior government posts.
The provisions of this law mean Berlusconi did not have to appear in a trial in which he was facing charges of bribing a witness. David Mills, his lawyer and former husband of Blair government minister Tessa Jowell, has been sentenced to four years and six months imprisonment for accepting a bribe. On 6 October, the constitutional court is due to issue a ruling regarding the constitutionality of the Alfano bill and, should the court rule that it is indeed unconstitutional, then Berlusconi will be obliged to stand trial for allegedly bribing Mills.
I would like to conclude by appealing to the Guardian and the other foreign press not to allow the spotlight to move away from Italy and to continue to perform the same vitally important task that they have always performed in the past, namely the task of informing the public, a role that most of our media have abdicated from because they are no longer being allowed to do their job.