"We sometimes seize arms and ammunition," said a Taleban commander in south-eastern Afghanistan.
"We're using whatever weapons are left over from Russian times and we buy from different sources - Pakistan, Iran, Russia - wherever we can get them."
I met the Taleban commander, a veteran of 30 years of war, in a safe house - one of the typical mud-built, fortress-like houses of the south-east where a six-metre (six-yard) high wall protects an extended family all living in the same compound.
The night before, I had been woken by the noise of small arms and rocket-propelled grenades. A nearby government office was being attacked.
The Taleban are targeting main roads and towns.
Their tactics differ from the mujahedeen who, fighting the Soviet occupation 30 years ago, started by taking villages and building up "liberated" territory.
The Taleban's aim, said the commander, was to force the American army to leave.
"We're ambushing the Americans, planting roadside bombs. We never let them relax," he said.
He said their favourite weapons were Iranian:
"There's a kind of mine called the Dragon. Iran is sending it and we have got it. It's directional and very powerful."
The Dragon appears to be a local name for what is internationally called an Explosively Formed Penetrator.
As the commander testified, it can penetrate the armour of Humvees and even tanks.
He said it was only available to special groups and you had to have "good relations" with the Iranians to get it.
Former mujahedeen fighter Shahir - which is not his real name - said Iranian weapons commanded a premium price:
"The beauty of the Iranian-made AK47, for example, is that it can also fire grenades. It costs $200-$300 dollars more than a Kalashnikov made elsewhere."
Shahir said there were two routes for Iranian weapons to reach the Taleban.
"There are people inside the state in Iran who donate weapons. There are also Iranian businessmen who sell them."
Britain and America have also alleged that elements in the Iranian state are helping to fund the Taleban, but it is rare to get confirmation from the Taleban side.
The Iranian Embassy in Kabul denied the allegations, saying Tehran supported the government of Afghanistan.
The most common route for getting weapons is from Pakistan.
Extensive arms markets and a local industry grew up in the Tribal Areas in the 1980s when there was Pakistani, American and Saudi support for the anti-Soviet Jihad.
"Buying arms there is as easy as buying a couple of bags of sugar," said Shahir.
"You'll see one or two Kalashnikov rifles hanging up outside a shop to show it's selling arms. Inside there's everything that money can buy - grenade-launchers, guns, even missiles and mines."
The Pakistani border is open to arms and fighters.
This summer, al-Qaeda fighters, who have found a safe haven in the Tribal Areas, have streamed across.
"There are Chechens here," said the Taleban commander.
"Uzbeks, Iranians, Arabs, Iraqis, Pakistanis, Indians, Bangladeshis, even some Germans and British fighting with us."
He also spoke about another, even murkier route for arms:
"Often, Russian and Iranian weaponry comes from the north. The northern arms dealers are well-known men, some of them have links and connections with Iran and Russia from Jihad times. And yes, they are the ones who used to be fighting the Taleban. "
I travelled to the north of Afghanistan to find out more about this extraordinary allegation - that commanders who fought the Soviet occupation and later the Taleban were now arms dealers who were selling weapons to their old enemy, the Taleban.
The insurgency has been good for business, two arms dealers, interviewed separately, admitted. Demand was up, not just from insurgents, but also locally in the north.
Fear of a strengthening Taleban had created a burgeoning northern market for weapons.
One dealer said the big arms dealers were selling to the Taleban:
"Most are former mujahadeen commanders. They've grown rich from the opium poppy trade and they're well connected. They actually use police convoys to transport the weapons."
'Balance of power'
But the question remains - why would Northern Alliance commanders, however corrupt, want to sell weapons to their old enemies?
Why play such a dangerous game? Profits are good, dealers said, but were not the only reason.
"The big dealers are war criminals," said one dealer.
"They've killed people and stolen their land. They know that if the government in Kabul became strong and stable, people would be able to demand justice."
"And if the Taleban took over, there would be also consequences. So they want to keep the current balance of power. And meanwhile, they're feathering their nests."
Government officials in Kabul were candid about the problems they face.
Arms from Pakistan were the main source for the insurgency, said the Deputy Interior Minister, Gen Daoud.
He said that in the past authorities had seized weapons and ammunition being smuggled from the north to the south.
He admitted there was police corruption, but denied former mujahedeen or Northern Alliance commanders could be involved.
"Mujahedeen is a very holy name - you should not mention it in the same breath as the word criminal," he said.
However, Gen Farahai, head of counter-terrorism for the Afghan police, said commanders were involved:
"From the north, sometimes they're selling ammunition and weapons to the Taliban and other illegally armed groups. And from the south, drugs are coming."
Afghanistan has endured a bloody summer.
With the Taleban armed to the hilt and the insurgency sucking in weapons from every quarter, there is a sharp sense of fear in the air.