Gunmen ordered 16 off-duty Iraqi soldiers out of a truck in Latafiya, south of Baghdad, at the weekend and killed them, but signs are growing that the slaughter of all Iraqis in the army or police, or civilians working for the government, is leading to divisions in the resistance.
The split is between Islamic fanatics, willing to killing anybody remotely connected with the government, and Iraqi nationalists who want to concentrate on attacking the 130,000 US troops in Iraq.
Posters threatening extreme resistance fighters have appeared on walls in Ramadi, a Sunni Muslim city on the Euphrates river west of Baghad.
Insurgents in the city say that resistance to the Americans is being discredited by the kidnapping and killing of civilians. "They have tarnished our image and used the jihad to make personal gains," Ahmed Hussein, an imam from a mosque in Ramadi, was quoted as saying.
A further indication that the armed resistance may be losing momentum is a fall in American casualties since January when 127 US and other foreign troops were killed, compared to 40 in March and just 12 in the first days of April. The US says the number of attacks by the resistance is slightly down from 50-60 a day in January to 40-45 now.
At the same time, the US occupation is as unpopular as ever among Iraqi Arabs, going by the mass rally against it by 300,000 people in the heart of Baghdad on Saturday. Called by the Shia militant leader, Muqtada al-Sadr, it was the largest anti-American demonstration since the overthrow of Saddam Hussein. Effigies of George Bush, Tony Blair and Saddam Hussein dressed in orange prison jump suits were symbolically thrown down amid cries of "No, No to America! No, No to occupation!"
Opinion polls confirm that two-thirds of Shia Arabs - 60 per cent of Iraq's population - as well as an overwhelming majority of Sunnis want US troops to leave immediately or in the near future. The Kurds, a fifth of Iraqis, are the only community fully to support the US presence.
The resistance in Iraq has always been fragmented and, unlike many traditional liberation movements, it has never had a political wing. Some 38 different groups have claimed attacks on the US troops. The insurgents have also proved extraordinarily effective - far more so than the regular Iraqi army during the war in 2003 - killing 1,089 US soldiers and wounding some 10,000.
The key to the effectiveness of the resistance is that it has swum in a sea of popular support or acquiescence. However, often after an attack on Iraqi police or army recruits, furious by-standers have said to me: "Why are they attacking our own people and not killing Americans?"
The near universal antipathy to the occupation enabled marginal, unpopular or criminal groups opposed to the US to flourish. Islamic fundamentalists, commonly called the Salafi or Wahabi, were able to establish themselves in Sunni Muslim districts. Baathist officials, army officers and security men were swiftly able to establish guerrilla cells.
The extreme Islamic groups, typified by that led by Abu Musab al-Zarqawi, see themselves fighting a world full of "infidels", "apostates" and "crusaders" in which an Iraqi Shia or Christian was as worthy of death as a US soldier. When American troops allegedly damaged two mosques in Mosul, insurgents blew up two churches in the city in retaliation.
The Sunni sectarianism of the Salafi limited the nationalist appeal of the resistance and ensured that Shias supported the destruction of Fallujah by the US Marines last November.
The Sunni community as a whole is reassessing its options in the wake of the 30 January elections which it boycotted. It fears that a Shia-Kurd state, from which it is excluding itself, is developing. In an amazing turnaround, the Association of Muslim Scholars, an influential body often the political wing of the resistance, called last week for Sunnis to join the army and police. The Shia parties, for their part, are intent on gaining control of the Interior Ministry and Mukhabarat security forces.
The Sunni leaders know that, in many ways, the resistance has been very successful. Two years ago, US officials were airily speaking of a prolonged occupation of Iraq. It was only as guerrilla attacks intensified that they agreed to the elections in January. The Sunni leaders may now wonder what they have to gain by intensifying resistance at a time when US forces are on the retreat.