As an assessment of military strategy, support troops may not be the best indicator of what will work or not. But as a political matter, it surely matters that many more Americans will be sent to Afghanistan this year by Obama than the headline number. The WaPo has an excellent primer on this. The Obama escalation is already huge - approaching 68,000, double what Bush had when he left office. And yet the war machine demands yet more. This is an enormous human and economic investment that should only be made if we are sure it can work. And even McChrystal, to his credit, cannot and will not guarantee that.