One of the pleasures of the Green Zone is to walk into the manicured courtyard of the Ocean Cliffs facility, where the press center is located, and linger awhile, free of body armor, on one of the benches next to the fountain. The gates of Ocean Cliffs are well defended by Salvadoran contractors working for Triple Canopy, and past them is a cordoned-off street leading to the sepulchral al-Rashid Hotel. A few minutes of quiet in the courtyard, with the necessary security measures in my peripheral vision, perspective on how tense the Green Zone really is.

And so today someone blew up a Green Zone cafeteria where Iraqi parliamentarians were lunching. No confirmation yet, but the initial reports from AP suggest it was a suicide bomber. If so -- and even if the bomb was planted and detonated remotely -- that means someone in a uniform had to wave the bomber into the parliament building. I didn't visit the parliament, but getting into a facility like the U.S. Embassy chow hall requires passing through several tiers of security. You are scanned and frisked. Your papers are scrutinized. Your companions are questioned. Items on your person are confiscated, even without suspicion of their use for terrorism. It's a likely bet that someone guarding the facility, and quite possibly a beneficiary of our training, equipping and mentoring efforts, wanted the attack to occur.

Making matters worse, a massive truck bomb collapsed the al-Sarafiya bridge in the north of the city. This is the first successful attack with real military significance since the beginning of the surge. There aren't too many ways across the Tigris in that area, and it's bound to have something of a deterrent effect on either resupply or the mobility of U.S. or Iraqi forces who need to get from one side of Baghdad to the other. It may not be major, but it'll be a factor: No one wants to introduce predictability to his or her movements, and the loss of the bridge takes away an option. Add to that the cost of hardening the rest of the city's bridges to ensure that further access doesn't get lost -- which has the effect of frustrating Iraqis who already endure massive traffic snarls at the city's numerous checkpoints -- and we see an insurgent/terrorist strategy developing that displays real military sophistication.

UPDATE: From Time's Brian Bennett:

The metal detectors at the entrance to the Baghdad Convention Center, where Parliament is housed, were not operating Thursday, said the Interior Ministry official, who was suspicious of a wider plot.

If the metal detectors were really inoperative, whoever was in charge of security should have taken supplemental precautions. Bennett reports that the bomber was wearing a suicide vest, which even a half-hearted frisking should have been able to discover.

Meanwhile, the Islamic State of Iraq -- nee al-Qaeda in Iraq -- has taken responsibility for the attack. If Marc is right about the emergent contours of the Sunni insurgent alliance against ISI/AQI, then presumably much of its membership -- namely, the Islamic Army of Iraq and Hamas-Iraq -- won't have much of a problem with blowing up parliamentarians, whom they'd view as collaborators. (Late late update: I initially suggested that the faction of the 1920 Revolution Brigades that didn't become Hamas-Iraq was also anti-ISI, but that was the reason for the split. Sorry.)