Iraq invasion strengthened the militants

Car bombs have almost as long a history as the car. What has changed since the invasion of Iraq is that bombers targeting civilian targets in the West now have a popular base and access to expertise in the Sunni community of Iraq.

The invasion was seen as an attack on Muslims as a whole by at least some Muslims in every country, who are willing and able to construct and deliver bombs. From the moment foreign armies were ordered into Iraq, al-Qa'ida was bound to be the winner.

US spokesmen have long blamed al-Qa'ida for every attack in Iraq but in fact the Salafi, proponents of a puritanical and bigoted variant of Sunni Islam, and the Jihadi, willing to wage holy war, belong to many groups,

The al-Qa'ida of Osama bin Laden was a surprisingly weak organisation in Afghanistan and Pakistan before 2001. To make the blood curdling videos of militants training that are frequently shown in documentaries, al-Qa'ida had to hire local tribesmen.

It is in Iraq that al-Qa'ida has come into its own. The US proclamation of the group as its most dangerous enemy served only as effective advertising among young Sunni men. Such denunciations also made it much easier for al-Qa'ida to raise money in Saudi Arabia and the Gulf.

The three car bombs used in Glasgow and London are far inferior to anything used in Iraq. This is an ominous pointer for the future because Iraq is now full of people who know exactly how to make a highly-effective bomb - and the means to detonate it. It is only a matter of time before this knowledge spreads.

The expertise of the Iraqi bombers attained a high level almost as soon as the first explosions occurred in Baghdad in August 2003. The Jordanian embassy was attacked and then the UN headquarters. Assassination by suicide bomber began with the killing of Mohammed Baqir al-Hakim, the leader of the largest Shia party, the Supreme Council for Islamic Revolution in Iraq, along with 85 of his followers in Najaf. By November, Jihadists were able to attack half a dozen targets at the same time.

There also appeared to be an endless supply of suicide bombers from Saudi Arabia, Jordan, Egypt, Syria and almost every state in the Arab world. The one Muslim country that suicide bombers did not come from was Iran, though the Iranians have been far more vigorously denounced than the Sunni states that produce the bombers.

In the immediate aftermath of the latest bombings in the UK there were immediate suspicions that Iraqi methods had spread. The opposite is true. It is surprising, given that one of the alleged bombers comes from Jordan, home to one million Iraqi refugees, that they did not know more about making a bomb. It is the political not the technical influence of the Iraq war that we are now seeing.