LONDON, England (CNN) -- Britain's defense secretary Wednesday mourned the deaths of seven British soldiers killed over the last week in Afghanistan and defended the hard-fought mission against Taliban militants.
British Defense Secretary Bob Ainsworth said Wednesday that more troop losses are likely in Afghanistan.
But Bob Ainsworth, speaking at the Royal Institute of International Affairs in London, also said "the nature of the fight" against a "highly adaptable" enemy "means we will take more casualties before we succeed."
"It is understandable that at a time like this people ask why are the lives of these courageous people being lost? Why are we in Afghanistan? In these difficult times, can we afford to be there? As defense secretary, I have a responsibility to answer these questions," he said.
He said if Britain leaves Afghanistan now, the Taliban -- which in 2001 ruled Afghanistan and harbored the al Qaeda terror network that attacked the United States --"will take control and al Qaeda will return."
"This is why some 9,000 British personnel from all three services are in Afghanistan. This is why they are risking their lives for us," he said. See photos from Maj. Sean Birchall's funeral »
The number of armed personnel who have died in Afghanistan since 2001 is 176.
Seven British soldiers have been killed in Afghanistan, since July 1, with the latest being a service member killed in an explosion in Helmand province on Tuesday during Operation Panther's Claw near Gereshk.
The U.S. military suffered eight troop deaths in Afghanistan Monday and Tuesday.
Ainsworth referenced British troops who sacrificed this week:
"One, the most senior Army officers we have lost since the Falklands. One, a young man of 18, the week before his 19th birthday. One I knew personally, the others I didn't. Each one is a personal tragedy for their family, their friends, and their comrades."
Ainsworth reiterated that Britain's military role in Afghanistan began after the September 11, 2001 attacks on the United States which he said were "a clear threat to our national security."
"We removed that threat by removing the Taliban and the terrorist training camps. And we act now to prevent the threat returning."
In addition Britain's role is to "prepare the way" for presidential elections in August and "provide the time and space" for Afghan security forces to security responsibility, he said.
"Our challenge is to support the Afghan national government until it can tackle the threat posed by the Taliban on its own. Because for Britain to be secure, Afghanistan needs to be secure," Ainsworth said.
British troops are based in Helmand province, where U.S. Marines are now leading an offensive against the Taliban. He said that when British troop deployed there in 2006, the government "had little control over the areas outside the provincial capital, Lashkar Gah."
"Today, eight out of the 13 districts in the province are under Afghan control," he said.
Ainsworth stressed the importance of separating insurgents from the people and avoiding civilian casualties. He also said it will take time and patience to build a potent security force.
"The goal is lasting security," he said. "That is why so much effort is being put into training the Afghan security forces. The national police force numbers over 80,000, the Afghan National Army is now nearly 90,000 strong and 2,000 more are being trained per month."
At the same time, he said there is no pure military solution to the conflict.
"Good governance, at national, provincial and local level, is necessary to meet the needs of the people," he said. "The military create the security space, the civilian effort develops, builds and strengthens."
And he stressed the importance of working with neighboring Pakistan. He said Foreign Secretary David Miliband "is in Pakistan as I speak" discussing the latest offensive in "Waziristan and the problems of the tribal areas."
"We are encouraging and advising the Pakistani government on the adoption of a comprehensive approach to the border regions which combines military action against militants with a plan for reconstruction, development and political reform."