Brits out and logistics questions

Patrick Lang over at Turcopelier is passing along the following story from the UK Telegraph concerning British troop drawdowns...

An entire brigade of 3,500 US troops is being lined up to replace British forces as they pull out of southern Iraq, the Sunday Telegraph has learned.

The US soldiers are expected to move south early next year, when Downing Street hopes to begin a scale down that will lead to a complete departure. Iraqi sources last night confirmed earlier reports that Britain would pull its remaining 500 troops out of Basra Palace - the last remaining garrison in the city itself - in a matter of days, paving the way for a full scale withdrawal in the coming months.....

The British are leaving Iraq as their military and more importantly their public support for prolonged, casualty taking engagement in Iraq is near nil. The British Army and Royal Marines are currently double-tasked beyond their sustainable capacity between Iraq and Afghanistan, and the British government's decision is that there is a chance in hell of a positive outcome in Afghanistan combined with greater public support, and that is where they are placing their bets.

Joe Klein earlier this week passed along the LA Times report that the Pentagon's goal was to reduce the US force footprint in Iraq to ten brigades by this point next year instead of the current twenty brigades. He claims that this means leaving Baghdad and concentrating forces elsewhere. To me this makes no sense on a logistical point of view, and the news that a US brigade is shifting to Basra reinforces that opinion.

The most important part of the dispute is what happens if we actually reduce from 20 to 10 combat brigades: We would have to leave Baghdad, which would, in effect, turn the city over to Muqtada al-Sadr.

This is a question of logistics as a quick glance at this map of the Iraqi road network makes clear. The roads over which the US supplies itself predominately run through southern Iraq, go past Basra, and then up the river valley to Baghdad, from there they branch out to the rest of the country. The US has a massive network of bases in the Greater Baghdad area that are there solely to distribute supplies. If the McClatchey analysis is true, that insurgent and crimimal groups (currently co-belligents with the US)control the Anbar road network, and tensions remain high between Turkey, the Kurds, the Iraqi government and the US, the northern and western supply routes are severely constrained.

The US can not supply its own forces if the road network from Kuwait to Baghdad is cut. That is why a US brigade will be backfilling for the British. That is also why I think any drawdown to ten or twelve brigades under anything resembling post-April 2004 conditions and violence environment means the US has to abandon Anbar, and north central Iraq. A brigade may be kept in Kurdistan if the combination of overland resupply and air resupply is plausible. Most of the US forces in a group of ten combat brigades would be needed for either direct supply line maitenance, base defense/force protection, or local patrolling to keep the supply lines open. That means Baghdad is still the logistical center of gravity for the US as that is the major hub.