US forces increasingly appear to be facing a more sophisticated and widespread insurgency. The most visible source of opposition continues to be radical cleric Moqtada al-Sadr and his Mehdi army in the Baghdad suburbs. But medium-term concerns are raised by the tactic adopted by the US-led coalition forces of ceding control to insurgents in a number of cities outside Baghdad, including Fallujah and other towns in the Sunni triangle.

US Secretary of State Colin Powell acknowledged the coalition's difficulties in reclaiming control of the extremist-held areas but stressed President Bush's administration was committed to making Iraq stable ahead of the January elections. 'Prime Minister Iyad Allawi is determined to go forward with these elections,' Powell said. 'Our strategy for the next several months, our political and military strategy, will be to recover each of these places and put them firmly back under the control of the Iraqi interim government so that elections can be held.'

The upturn in violence began on 12 September in a series of attacks. At least 25 Iraqis were killed in four suicide car bombings and a barrage of rocket and mortar fire in several Baghdad neighbourhoods. US forces responded the following day with air strikes on Fallujah, killing 16, in an attack it claimed was aimed at key supporters of wanted Jordanian militant Abu Musab al-Zarqawi. US forces also reported engagements in Talafar, an area the US military has claimed is a base for foreign fighters crossing from Syria into Iraq.

The violence worsened on 14 September as insurgents repeatedly targeted Iraq's fledgling police force. A massive car bomb exploded near a Baghdad police station, killing at least 47 people and wounding 114, as dozens of would-be police recruits queued to join the force. Later the same day in Baqubah, gunmen opened fire on a van carrying policemen home from work, killing 11 officers and a civilian.

Iraq's oil industry remains a prime target. Also on 14 September, saboteurs blew up a key junction where multiple oil pipelines cross the Tigris river near Beiji in the north, setting off a chain reaction in generation systems that left the entire country without power.

Since the Bush administration handed over power in June to Iraq's interim government, its disengagement plan - to strengthen Iraq's administration through a build-up of army, civil defence and police corps so that it can take over security from coalition forces ahead of January elections - has become strained.Instead, it struggles to stay in control of several areas, and the more worrying effect of allowing extremists to control Fallujah, Ramadi and towns in the Sunni triangle is that the US has allowed the establishment of an insurgency haven in central Iraq.

If not subdued militarily, rebel forces in these areas may well continue to defy the interim government and refuse to participate in the January elections. This could lead to the serious consequence of having fewer Sunni participants in the political process and further undermine the legitimacy of the political transition.