Defense Secretary Reid, speaking in Kabul, said Britain would continue its efforts in Afghanistan.
"So when we come to work shoulder to shoulder with the democratically elected government of President [Hamid] Karzai, we are not only contributing towards your efforts of taking control of your own country, sovereignty, building your own economy and security forces," Reid said. "But we also protect our own people by making this a safer world. We both benefit."
Reid said that the greatest danger of all for the people of Afghanistan would be if Taliban regime comes back to power.
Reid's visits come as suspected Taliban militants attacked a construction company in southern Afghanistan today, killing one security guard and destroying 14 vehicles. The attack happened in Kandahar Province, on the Oruzgan-Kandahar highway, near a village where four Canadian soldiers were killed in a suspected Taliban bombing yesterday.
Elsewhere, another three suspected Taliban militants and one policeman were killed in a gunfight in Ghazni Province, some 125 kilometers south of Kabul.
Reid, who arrived in the capital early today, said security has its price.
"That safety has a price, and that price, tragically, is paid sometimes in lives taken by terrorists and I therefore remember today and pass condolences to the families and the loved ones of all of those who have died since my last visit, including brave members of the Afghan forces, most recently of course, multinational forces."
Reid rejected as "absolutely and completely untrue" media reports that Britain had been asked to send an extra 600 troops. Reid also stressed the distinction between the NATO-led peacekeeping force and the separate U.S.-led force hunting militants.
"The Operation Enduring Freedom, which is the antiterrorist, the counterterrorist mission, [is] controlled and led by the Americans," Reid said. "There is a second mission, which Britain is playing a major part in the south, which is the reconstruction of Afghanistan by multinational forces, including the British, helping the government of Afghanistan and civilian agencies to build the economy, build the democratic government and build their own security forces."
'Three More Years'
Reid suggested that British troops would remain in Afghanistan for at least three more years. He said British forces would be "perfectly happy to leave in three years time without firing one shot because our mission is the reconstruction [of Afghanistan]."
Britain has some 3,000 troops in southern Afghanistan as part of a NATO-led force currently numbering about 10,000.
Along with the British troops, Canadian, and Dutch soldiers have started deploying in the south, which borders the mountainous frontier with Pakistan, believed to be a haven for Taliban and Al-Qaeda fighters.