The BBC's Andrew North is spending the week with US troops in Ramadi, the capital of Anbar province and a stronghold of the Sunni insurgency. He will be filing updates later in the week. Here is the first of his reports.
Ramadi has been a centre for violence in the Iraq conflict
Ramadi, Anbar province. "The worst place in the world."
That is how a Marine sergeant described it to me once.
It was last year. We were at a landing strip in Fallujah just 30 miles away, talking as we waited for helicopters.
He had served in both places. Ramadi had been far worse, he said, glad to be on his way home.
"We were attacked every day. It was insane," the sergeant said, shaking his head. "We lost a lot of guys."
I remembered that conversation as we flew towards Ramadi from Baghdad in the small hours of Sunday by helicopter, watching the two gunners as they scanned the darkness below through night-vision sights.
We have come to this stronghold of the Sunni insurgency to see if things are changing.
This city of some 400,000 people has been an almost permanent battleground since the US invasion. A beacon of defiance for insurgents, a constant thorn in the side of the US military.
Built on the River Euphrates, it is capital of Anbar province. Many former officers from Saddam Hussein's military live here. When it was summarily disbanded in 2003 by US administrator in Iraq Paul Bremer, many joined the insurgency.
But while US forces succeeded in subduing nearby Fallujah - at great cost - Ramadi has appeared un-winnable. At times last year, it accounted for half the insurgent attacks in Iraq. Al-Qaeda controlled whole districts and declared its own Islamic state.
But American commanders say things have started to change. Al-Qaeda and other insurgent groups are now on the back foot, they believe.
Several of the key tribes of the area have turned against them.
These are early days. There have been optimistic predictions before and the insurgents have proved time and again their ability to adapt.
'Welcome to Camp Ramadi'
The US Marine transport helicopter flew in by night to reduce the risk of attack.
When we land, the gunners urge us off quickly. They do not want to hang around.
We jump from the ramp into thick mud. It has rained, turning the desert sand here into a heavy clay, which coats everything.
"Welcome to Camp Ramadi." A young soldier woken from his bed to meet us appears out of the gloom.
This is just our first stop, the main base on the city outskirts.
After spending the night in a converted container, soldiers from the US Army's 5-7 Cavalry squadron drive us to their base in north Ramadi.
According to US troops, security is better but there are still threats
In this area, the US focus is almost all hearts and minds, primarily through shoring up the local authorities.
A local council of tribal sheikhs, who have come out against al-Qaeda, has been set up to co-ordinate local needs.
US money is going into new schools and literacy projects. New police stations are being established.
"Security is better," the local commander, Lt Col Clifford Wheeler, says.
"The units in this area last year were being IED'd [targeted by improvised explosive devices] on a daily basis. Now we can go most places round here without being attacked."
But there are still threats.
Some of his soldiers were caught by a suicide bomber on the northern edge of Ramadi last Friday who used chlorine gas, one of several similar attacks in recent weeks.
In the distance, we hear the crack of machine-gunfire as night falls and the low buzz of a surveillance drone overhead.