Bases captured but abandoned are now being retaken by US marines
Three months after British forces in Afghanistan handed over control of Sangin to the Americans, reporter Ben Anderson went on patrol with the US 3rd Battalion 5th Marines "Lima Company" in the area still widely viewed as the country's most dangerous.
No-one knew it yet, but we were standing on a "daisy chain" of seven home-made bombs, buried inches beneath our feet and designed to wipe out the entire squad of US marines.
The bombs were attached to a wire, which led down an alleyway off the path we were nervously inching along.
Somewhere, someone with a battery at the other end of that wire was watching us, waiting for the perfect moment to connect the circuit and detonate the bombs.
We had tried to avoid walking through this very corner, knowing full well such obvious routes are favoured by the Taliban in placing their IEDs. But there was no other way forward.
Roughly 20 metres past the corner, there was a huge explosion behind me.
PANORAMA: FIND OUT MORE
Ben Anderson reports from Afghanistan
The Battle for Bomb Alley
BBC One, Monday, 31 January at 2030GMT
I turned and saw the air thick with swirling dust. Stones and rocks started landing all around. As the air began to clear I saw a crater, and could hear someone groaning.
I walked back and saw a marine known as "Big T" on his hands and knees, patting the ground around him, trying to work out where he was.
Somehow, no one had been killed - the marines walking behind me were all standing between the IEDs when they went off.
Big T was severely concussed, and temporarily blind and deaf. Two others had been badly shaken, but it seemed miraculous that no one was dead. It was four days after Christmas.
The area claimed the lives of 106 British soldiers in four years.
In the three months since the US forces took over from British troops, more than 20% of the combat power of 3rd Battalion 5th Marines in Sangin have been killed or injured.
The town's reputation as the most dangerous place in Afghanistan is undimmed by the arrival of Marine muscle and firepower.
So far, 27 have died and more than 140 have been injured. These numbers are staggering, even by Sangin standards.
The casualties are far worse than those suffered by any British forces in such a short time.
But did the US Marines have to be doing this at all?
Incredibly, British soldiers had cleared the same route, Pharmacy Road, almost 18 months ago.
Bomb disposal specialist Olaf "Oz" Schmid was posthumously awarded the George Cross for clearing this very area of IEDs.
In a single day in October 2009, he cleared 31. He was killed doing the same thing a few days later.
His efforts ensured British soldiers were able to establish bases just 400 metres from where I now stood in Sangin, in a maze of alleyways and high walls called Wishtan.
But when the Americans took over in October, they abandoned them, believing that too many bases would spread them too thin.
Oz Schmid died while defusing his 65th bomb in Afghanistan
Now they have decided that giving up Wishtan was an error.
And while in the past both the Americans and British forces in Sangin have tried to put the lives of the local civilians first, now the Americans had decided on a different approach.
Once they re-established the former British base, bulldozers appeared and started flattening the walls and compounds on either side of Pharmacy Road.
A mosque across the road from the new base was one of the buildings demolished.
The two men who said they owned the mosque pleaded to be allowed to remove everything inside, and quickly retrieved some Korans, a gas heater and a rug before the building was reduced to rubble.
I asked the marines' Commanding Officer, Capt Matt Peterson, if this tactic risked pushing the locals into the arms of the Taliban.
"Short term there is a sacrifice of convenience to an extreme degree, and that's not something that's lost on us. But I think what people understand is that in order to increase security on that route and in order to prevent the enemy from putting any IEDs there, these types of drastic steps are necessary."
A local mullah disagreed.
"Can democracy be brought by a cannon? Is that what the meaning of democracy in the world? We don't want this democracy. We don't want this law of the infidel, we want the rule of Islam."
British forces spent four years in Sangin district of Helmand province
After four years of increasing levels of violence and increasing numbers of casualties, on all sides, it feels as if hearts and minds cannot be won here.
Capt Peterson is determined that the marines will prevail here and his message to the insurgents is clear.
"We are never going to quit, there are not enough IEDs to keep us from patrolling. You don't have enough bullets to keep us from accomplishing our mission."
Capt Peterson said the recent decision at the Lisbon conference, which put the deadline for Nato's withdrawal at 2014, later than many expected, will have a decisive effect on the ground.
"I think when the enemy saw that, at the lowest level that demoralised them to the point where he said, 'Well, we can't continue to fight him because he's better than us. We can't outlast him because he's not leaving. We'd better figure out a way to carve our way into the future of Afghanistan or we're going to get get left out in the cold.' And if that's his analysis he's exactly right."
The spring months, which are expected to mark an increase in fighting here, will either prove Capt Peterson right, or show that victory in Sangin is as far away as ever.
Panorama: The Battle for Bomb Alley, BBC One, Monday, 31 January at 2030GMT and then available in the UK on the