Baghdad's traffic was ever an entertaining experience. If a traffic jam took up the full three lanes, it was not unknown for a driver to do a U-turn and then reverse to his destination against the oncoming traffic. Nowadays, almost every morning except Fridays, Baghdad drivers swelter in hooting, crawling gridlock around Sadoun Street and the bridges across the Tigris.
The reason is simple: the Americans, in their terror of attack, have blocked themselves off from the rest of Iraq. To do this, they have completely closed the north-south access of the west bank of the Tigris, starting at the 14 July Bridge. Wire-mesh-and-fabric bollards filled with sand cut off more than six major roads leading to the arteries around the former presidential compound now ironically known among Iraqis as "Bremer Palace".
To get into the hub of the Coalition Provisional Authority's public offices, Baghdad's Conference Palace, you must pass through six checkpoints and undergo three body searches. The building where the sycophantic National Assembly used to meet can now be described only as "fortified", but certainly does more business than in the old days. When eventually you do get inside, you find the US Agency for International Development offices on the second floor, at the back and on the right.
Several eye-catching display boards in the reception area are astonishing for what they show: not plans and pictures of projects undertaken to "reconstruct" Iraq, but the designs of the new living quarters for Usaid personnel, deep in the former presidential compound.
The display boards are indicative of how the American administration of Iraq has positioned itself - isolated and insulated from the people with whom it needs to connect. As the body bags returning to the US daily testify, the Americans are rightly terrified of that contact. To increase their protection, they turned to the Israelis, the regional masters of separation. The whole presidential compound is now surrounded by a 30-foot-high wall of the type of concrete segments I last saw around Qalqilya on the West Bank.
But as the recent attacks on the Jordanian embassy and the UN headquarters in Baghdad show, you can't be too careful. The terrorists who seek to make Iraq ungovernable are sophisticated and determined. It would seem that many of Iraq's neighbours are following the Bush doctrine of the pre-emptive strike, using Iraq's instability to have a go at the Americans wherever they can.
"The US has underestimated the power of the apparently weaker party in asymmetric warfare," says Paul Eedle, an al-Qaeda watcher and expert on Islamic websites. He believes that, as in Beirut during the Lebanese civil war, it is in the interests of Syria, Iran and Saudi Arabia to back shadowy cells not strictly within the ambit of the jihadi movement.
Eedle suspects that the group claiming responsibility for the UN headquarters attack, the Armed Vanguard of the Second Army of Muhammad, is not really a jihadi splinter, but may rather be the creation of a foreign intelligence service. "It has no profile among the network of jihadi groups and chatrooms on the web, and they all know each other," he says.
So will concrete and razor wire do the trick? As the Israelis are finding out, fencing yourselves in is no guarantee of safety and never addresses the problem. As long as the US administration remains remote, Iraqis will continue to think the occupation is peripheral to their existence. When I stopped Iraqis at random and asked them to explain the situation in Iraq, one man described how the country "had been controlled by a devil" who was now gone. "Today, people are reconstructing their lives," he finally said. The most striking thing about his whole description was that the Americans did not feature once.
Tim Lambon is a producer with Channel 4 News in Iraq