KARADEH used to be an affluent shopping area of Baghdad. It boomed for a while after the American invasion as goods flooded into Iraq after years of sanctions. But as sectarian violence intensified, the store fronts became shuttered and shell-pocked.

In a vote of confidence in the surge by US troops, the shops were reopening last week. Hareth Salah, a 24-year-old student, said he had stopped attending courses at his technical college when the surge began last month.

“One of my friends was killed by the terrorists,” he said, “but now there are a lot more Iraqi army checkpoints and I’m feeling more secure. I feel better; I can go out and do my shopping. More people have opened their stores and the markets are open longer.”

As the fourth anniversary of the Iraq war approaches on Tuesday, progress remains uncertain but trends are hopeful.

“This is a bit of a rollercoaster ride,” said General David Petraeus, the US commander in Iraq. “You’re trying to do what is necessary to keep the rollercoaster generally going up, despite the ups and downs and the bumps.”

Murderous sectarian checkpoints have melted away as the Iraqi security forces and American troops extend their grip on the capital. Abu Mohammed, a 34-year-old taxi driver, who lives in the largely Shi’ite Sha’ab district in northern Baghdad, said: “Sometimes I would stop and wait for an hour or two rather than take a chance on passing a fake checkpoint with a customer.

“We were so scared; anybody could be followed and assassinated.”

Figures released last week by Brigadier Qassim al-Moussawi, an Iraqi military spokesman, showed civilian deaths down from 1,440 in the four weeks before the surge began on February 14 to 265 in the four weeks that followed, although there may have been some undercounting. According to the American military, assassination attempts were down by 50%.

The number of US deaths was also down, from 87 to 66, although the concentration of troops in Baghdad led to an increase of 12% in fatalities in the capital.

Frederick Kagan, a military historian and leading advocate of the surge, said: “It is very early days but I’m very encouraged by what is happening. America only has two brigades out of five there and we haven’t even started our major operations yet. I had not expected this little resistance.”

Residents of the Iraqi capital are holding their breath. For each hopeful piece of news there seems to be a car bombing or attempted assassination - such as one on the Shi’ite mayor of Sadr City last week - that threatens their security.

“At least I don’t see bodies thrown here and there on the road, as in the days before the security plan,” said Ramya Ahmed, 35, a Shi’ite living in Adamiya, a largely Sunni neighbourhood.

A demonstration on Friday by militants loyal to the Mahdi army of the Shi’ite cleric Moqtada al-Sadr shouting “No, no to America” has raised fears of a new outbreak of hostilities with the cleric’s blackshirts.

Vali Nasr, an American expert, said Sadr was still growing in authority. “It is very clear the Mahdi army made a strategic decision not to engage the Americans in Baghdad,” he said, “but it has not been defeated. It is a tactical withdrawal.”

Roughly 700 members of Sadr’s militia have been arrested and others have fled to Iran. “Only the smaller people are left, so everyone is feeling more safe,” said one relieved resident.

American forces have moved with relative ease to install joint security stations with the Iraqis in Sadr City’s teeming slums. The number of these “mini forts” in Baghdad is due to reach 30 in the coming weeks. Some families displaced by ethnic cleansing have returned to check on their homes, although few have felt confident enough to stay.

Car bombings in Baghdad rose to an “all-time high” of 44 last month, according to a Pentagon spokesman, but troops are now fanning out to the suburbs and to outlying towns such as Baqouba in an effort to uncover bomb-making factories.

The Americans’ Stryker Brigade combat team was redeployed last week to the area, where there has been a sharp rise in attacks amid signs that Sunni insurgents are regrouping.

An extra combat brigade and more than 2,200 military police are being dispatched to Iraq, which by the end of May or early June will bring the number of additional US troops involved in the surge to 30,000. But James Carafano, a defence expert at the conservative Heritage Foundation, cautioned that an increase in violence was likely during the spring and summer.

“The first thing you would expect the bad guys to do is to go to ground, map things out, do some reconnaissance and figure out how to screw things up,” he said. “You have to get through to next winter before you can say the surge has worked.”

Suicide gas attack

Three suicide bombers using lorries loaded with chlorine gas killed eight people and caused 350, including six American soldiers, to fall ill in Fallujah and Ramadi this weekend.

The attacks prompted warnings that the insurgents are turning to new weapons to spread panic. Symptoms ranged from minor skin and lung irritations to vomiting.

Insurgents have detonated three other lorries carrying chlorine since January. Major-General William Caldwell, the American army’s spokesman, called it “a crude attempt to raise the terror level”.

Chlorine gas was deployed as a weapon in the first world war but its use has particular resonance in Iraq. Saddam Hussein turned chemical weapons on Kurdish areas in the 1980s during the Iran-Iraq war. Extra US troops have seen civilian deaths drop from 1,440 in the month before to 265 after

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