At their most basic level, as historian Carl von Clausewitz pointed out, military decisions are political. They rely as much on essentially political judgments of both the reliability of allies and the willingness of troops and civilians on both sides to take punishment as on military men's assessments of relative abilities to inflict pain.
Indeed, President Bush in enunciating on Wednesday a new course for Iraq admitted as much in arguing that this is "more than a military conflict. It is the decisive ideological struggle of our time". Limited new military muscle, in the form of 20,500 extra troops, would be only part of a programme to build the capacity of the Iraqi army and to woo Iraqis with extra jobs and reconstruction projects. But he has pinned his colours, in typical wishful thinking, to a political strategy that places enormous faith in both the intentions and competence of a deeply flawed ally, prime minister Nouri Al-Maliki, and in the latter's ability to do precisely what, up to now, he has shown himself incapable of.
Iraq's 80-per-cent Shia army, heavily infiltrated by militias, is hardly going to take on the might of Moqtada al- Sadr who is estimated to be able to call on some 60,000 fighters. "This time, Iraqi and American forces will have a green light to enter these neighborhoods - and Prime Minister Maliki has pledged that political or sectarian interference will not be tolerated," Mr Bush told America. Yet even if Mr Maliki intends to co-operate in, let alone lead, such operations he simply does not have an effective state apparatus for such heavy lifting or a political base that would acquiesce to it. Mr Maliki's own commitment to a democratic, multisectarian state is questionable.
The cynical might suggest that Mr Bush has set Mr Maliki up as the fall guy for the next round of breast-beating admissions of failure; that his mea culpa on Wednesday, "Where mistakes have been made, the responsibility rests with me" may become "It's the fault of the Iraqis - time to get out". On the broader diplomatic front Mr Bush, while acknowledging the regional dimension of the conflict, has decided not to take the advice of James Baker's bipartisan Iraq Study Group which called for "extensive and substantive" talks with Iran and Syria.
Unlike Tony Blair, he appears not to make any connection whatever with the need to defuse the Palestinian crisis, which merited only the most fleeting reference. Instead, he has reinforced the US naval presence in the region and will dispatch his secretary of state, Condoleezza Rice, next week to ensure his message is understood.
Nervous but sympathetic Arab countries are not reassured. They do not want to see the US cut and run, plunging Iraq into an even bloodier civil war that could spill over the country's borders. But, nor are they convinced by the "one big heave" argument of a president who has shown himself so persistently deaf to realities on the ground. His new turn is more of the same.