The US military has embarked on a new and risky strategy in Iraq by arming Sunni insurgents in the hope that they will tackle the extremist al-Qaida in Iraq.

The US high command this month gave permission to its officers on the ground to negotiate arms deals with local leaders. Arms, ammunition, body armour and other equipment, as well as cash, pick-up trucks and fuel, have already been handed over in return for promises to turn on al-Qaida and not attack US troops.

The US military in Baghdad is trying to portray the move as arming disenchanted Sunnis who are rising up in their neighbourhoods against their former allies, al-Qaida and its foreign fighters. But the reality on the ground is more complex, with little sign that the US will be able to control the weapons once they are handed over. The danger is that the insurgents could use these weapons against American troops or in the civil conflict against Shia Muslims. Similar efforts by the US in other wars have backfired, the most spectacular being the arming of guerrillas against the Soviet Union in Afghanistan.

Major General Rick Lynch, a senior US commander in Iraq, insisted no weapons would be given to insurgents who had attacked Americans. "We have not crossed that line," he said.

The US said it would use fingerprinting, retinal scans and other tests to establish whether insurgents had been involved in fighting against American troops.

But a reliable witness to a meeting this month between US forces and insurgents in the Sunni stronghold of Amadiya, in Baghdad, expressed scepticism about the strategy. Far from being a popular uprising against al-Qaida, only a handful of armed men turned up. The US handed over ammunition to them. The witness said that US soldiers watching the handover were dismissive, seeing it as a stunt.

The strategy was discussed in Baghdad this month between the new US commander in Iraq, General David Petraeus, and his field commanders. They decided to leave it to each commander to decide locally.

The Pentagon insisted the latest strategy was not recognition that president George Bush's "surge" policy had failed. All of the extra 30,000 US troops ordered by Mr Bush in January to Baghdad and Anbar province, one of the centres of the violence, had only just been fully deployed and it was too early to judge it.

Initial successes of the surge in pacifying parts of Baghdad have now been reversed, with the death toll among US troops and Iraqi civilians last month among the highest since the 2003 invasion.

The US military first tested the strategy of arming its former enemies in Anbar province. Anbar is now relatively quiet, but that could be because the US has flooded the province with US troops.

The Anbar model is being extended to Amariya, as well as Diyala and Salahuddin provinces.

The US insists that the Sunni disenchantment with al-Qaida is because of the group's suicide bombings that have resulted in the deaths of thousands of Iraqi civilians.

The arming of the Sunni insurgents reflects US unhappiness with the slow progress of the Iraqi army, which it suspects of being too close to the Shia militias, and with the police, which is even more riddled with sectarianism. At a press conference, Gen Lynch said he was concerned about corruption within Iraq's police force and by interference from the national government in security issues, particularly in the release of suspected insurgents held by Iraqi security forces.

Part of the problem is that the US needs its security efforts to be accompanied by political progress but the Iraqi coalition government has so far been unable to reach agreement on the biggest divisive issues. In a further upset, Iraq's Shia-dominated parliament voted yesterday to remove the speaker, Mahmoud al-Mashhadani, a Sunni, over alleged scandals. His bloc, the Sunni Arab Iraqi Accordance Front, was asked to submit an alternative.

The manoeuvring came on another day of bloodshed across the country, which left 36 Iraqis and three US soldiers dead. In a separate attack, a suicide bomber destroyed a bridge over the Diyala river, north of Baghdad.

Changing tactics

1999: Operation Desert Crossing

A series of war games conducted by the US in 1999 by General Anthony Zinni, who concluded that a force of 400,000 troops would be needed to invade and pacify Iraq. The US defence secretary, Donald Rumsfeld, instead plans for 130,000 US troops and 45,000 from Britain and elsewhere.

2003: Operation Iraqi Freedom

Codename for the US invasion. Britain called it Operation Telic. In May, President George Bush, right, declares hostilities at end, with a banner behind him saying "Mission Accomplished". Paul Bremer, the US head of the provisional government, disbands the Iraqi army, sending tens of thousands of trained and armed men into unemployment and potentially into the insurgency. The US denies there is a resistance. Saddam Hussein is captured on December 13, 2003 on a farm near Tikrit in Operation Red Dawn.

2004: The US battles Shia militia in Najaf and mounts a full-scale assault on Falluja to root out Sunni insurgents and take revenge for the gruesome deaths of US contractors.

2005: Paul Wolfowitz announces that 15,000 US troops whose tours of duty had been extended in order to provide election security would be pulled out of Iraq by the spring. There is a temporary reduction in violence.

2006: Mr Bush points to the success of a US commander, Colonel HR McMaster, in Tal Afar, near the Syrian border, as "the outlines of the Iraq we've been fighting for". Col McMaster cut off Tal Afar, divided it into small neighbourhoods and established permanent posts in them instead of defeating insurgents and then leaving. In October the US military announces that Operation Together Forward has failed to stop violence in Baghdad. The Iraq Study Group, made up of former US politicians and officials, proposes a troop reduction.

2007: Mr Bush ignores the Iraq Study Group in favour of a 30,000-strong "surge" in US troops to pacify Baghdad and Anbar province. Tony Blair announces that following the success of Operation Sinbad in the British sector, the UK will reduce its military presence. Mr Bush appoints Lieutenant-General Douglas Lute to coordinate Iraq and Afghanistan. The surge, after an initial reduction of violence in Baghdad, has in the last two months had little impact, with the death toll last month one of the highest since the invasion. The US opts for arming its former enemies, Sunni insurgents, to try to split them from the more extremist al-Qaida in Iraq.