The first sign of the attack was somewhat mystifying: a tractor suddenly going up in flames on farmland beyond the base.

But there was no ambiguity about what followed. A group of men charged, the first blowing himself up as he reached the fence, the others behind opening up with rifle fire. At the same moment, the first of a salvo of rockets launched from a distance landed inside Kandahar airfield.

It lasted no more than a few minutes. Once the tractor packed with explosives had prematurely detonated, there was little chance of the Taliban fighters getting through, their suicide vests exploding as the western troops cut them down. As the gunfire ended, and the smoke and fire began to clear, body parts and dismembered heads could be seen lying amid the unused arsenal – rocket-propelled grenade launchers, hand grenades and Kalashnikovs.

There was no intrinsic military gain for the insurgents in the assault, a fortnight ago, with only a 4ft-wide hole in the fence to show for five deaths. There was little chance of escape for the fighters even if they had turned back, with a dozen warplanes and helicopters already overhead. But it had propaganda value, with some news reports declaring a "complex operation" which "led to a fierce hour-long firefight". The fact the target was Nato's airbase at Kandahar, the spiritual home of the Taliban and scene of the next major US-led offensive, gave it greater resonance.

"But what a waste of lives, blowing themselves up at a fence, what's the point of that?" asked Wing Commander Ash Bennett, of the RAF Regiment, whose troops provide security at the base. "Why don't they talk to us instead? At the end of the day, this thing will have to be settled by talking."

Whatever the ideal, though, there is little doubt there will be a lot of bloodletting in Kandahar before the talking beg­ins. Clearing Kandahar was one of the main goals of General Stanley McChrystal, the US commander of Nato forces in Afghanistan, before his sacking by Barack Obama. It is now the first big test for General David Petraeus, his successor.

Petraeus has stated he does not consider himself bound by a July 2011 deadline set by Obama to begin the withdrawal of US forces. It is highly unlikely that any large-scale pull-out can take place until the Kandahar region has not only been reclaimed but held, to prevent the Taliban from infiltrating back into the area.

There are contentious factors at play in Kandahar. Powerful local strongmen hold sway in large parts of the area, running private armies, seemingly not answerable to authority. The most high-profile and controversial of these is Ahmed Wali Karzai, the brother of the president, who is accused of running his fiefdom like a Mafia boss.

Even without the Nato clearance operation getting underway, the tempo of action is rising now that the poppy crop has been harvested. "There's little doubt we are facing a very hard summer, it's not going away, we are facing a tough enemy," Bennett acknowledged.

British forces can provide something lacking in other parts of Afghanistan – continuity. The RAF Regiment had been providing security for the airbase and surrounding area for many years. "They know us and we have built up a relationship," said Squadron Leader David Caddick.

But cooperation with western forces and the Afghan government can be dangerous. The Taliban has killed over 500 tribal elders, religious scholars and elected representatives in the last six years and with the impending Nato offensive, has stepped up a campaign of assassinations against locals expected to help provide governance.

Women in Kandahar have suffered the most under the Taliban. Many in public life have been murdered, among them Safia Amajan, the highest-ranking public official in southern Afghanistan, and Commander Malalai Kakar, a police officer who ran a unit re­scuing abused women. Zar­ghuna Kakar, an MP, had to flee after her husband was killed and a daughter injured in an ambush. Before the shooting, Kakar had repeatedly pleaded for security.

She turned in desperation to Ahmed Wali Karzai. "He told me there was nothing he could do," she recalled. "He also said that I should have thought about what may happen before I stood for election. But it was his brother, the Americans and the British who told us we women should get involved in political life."

At present, there simply are not enough Afghan security forces to provide security and the gap is being filled by private companies run by local power brokers like Ahmed Wali Karzai. Major General Nick Carter, the British commander of Nato forces in southern Afghanistan, stress­ed that much progress had taken place since low-level, security operations got underway in Kandahar last April.

But he continued: "The nature of the problem in Kandahar city is one characterised by Moscow in the 1990s. When you needed a patron, mobs and the mafia prevailed, protection rackets were the order of the day. Within that environment it's very easy for the insurgents to intimidate and threaten.

"But I would hope by the time the parliamentary elections come around [mid-September], Kandaharis would feel a little bit more secure. I'm a great believer in doing things quietly, under-promising, then hopefully overachieving."

Kandahar City Timeline

Winter 2001: Taliban forced from city by US Special Forces with Afghan allies

Spring 2004: Revitalised insurgent force fails in major offensive to take back city

Summer 2005: Ahmed Wali Karzai, the president's brother, becomes city's key powerbroker

Winter 2006: Canadian troops take over responsibility from US

Summer 2008: Taliban gain control of areas 10 miles west of Kandahar City

Summer 2010: With Canadian forces due to withdraw next year, allies consider moving British troops from Helmand