That the Afghan campaign lacks a clear strategy, has been politically misdirected and militarily under-resourced, and is essentially unwinnable as presently conceived is something the British public, like its counterparts in the US and western Europe, has increasingly suspected. Opinion polls in most Nato countries show strengthening opposition to the western alliance's longest ever war.

The war logs, an official accounting of murderous missions, tragic incompetence and abject failure from 2004-2009, put factual flesh on the bare bones of these negative perceptions. Their publication may further undermine public support just as the campaign supposedly reaches a "critical" juncture following June's record casualties and the sacking of General Stanley McChrystal.

The White House's defence – that this serial bungling occurred on George Bush's watch – appears problematic. Since Barack Obama concluded a policy review last December and decided on a "surge" of 30,000 additional troops, overall levels of violence have risen further while confusion about counterinsurgency strategy and the exit timetable has deepened.

"Obama has had several opportunities to reassess US goals and interests and in each instance he has chosen to escalate," said Richard Haass, a former senior Bush administration official and president of the council on foreign relations. "Today the counterinsurgency strategy that demanded all those troops is clearly not working." Afghanistan was now Obama's war, Haass said, and he was losing it. "It's time to scale down our ambitions and reduce and redirect what we do."

American and therefore British aims have already been pared down considerably. Less is heard these days about institution-building, transparent, corruption-free governance and grandiose infrastructure projects. Talk of "victory" over the Taliban has been replaced by furtive talk of talks. The war aims of the world's most powerful military alliance have now boiled down to three fingers-crossed wishes: create a relatively stable, self-governing state, ensure it no longer harbours al-Qaida, and then get the hell out of Dodge.

The appointment of the Iraq war hero, General David Petraeus, as McChrystal's replacement, has so far only compounded the confusion about how even these modest objectives can be reached. Though he will not say so in public, Petraeus, as head of US central command (Centcom), did not support Obama's July 2011 deadline for beginning US troop withdrawals.

At his congressional confirmation hearing, Petraeus indicated he favoured a troop-intensive strategy (as in Iraq) and would privately press for more time and a slower withdrawal schedule that will keep most of the troops in Afghanistan for longer. Petraeus is in the driving seat and Obama knows it. After twin fiascos over McChrystal and his predecessor, General David McKiernan (also fired by Obama), he is virtually unsackable. What he wants he will most probably get.

Trouble is, it's uncertain Petraeus knows himself when it comes to the specifics. He wants more emphasis on training up Afghan army and police to take over security responsibilities. But contradicting previous forecasts, Petraeus's aides say he does not believe the Afghans will be ready this year.

Petraeus wants to give more responsibility to friendly tribal leaders, as he did in Iraq's Sunni triangle; President Hamid Karzai opposes the idea, saying it will encourage warlordism. Petraeus says he wants to amend rules of engagement, giving US forces (who have been complaining they are hamstrung) a freer hand to call in air strikes and artillery when under fire. At the same time, he says he remains committed to minimising civilian casualties.

And Petraeus looks likely to pursue the expansion of the war into Pakistan's tribal areas, already subject to an increasing number of drone attacks and the occasional special forces incursion. The numbers of US troops based in Pakistan is small but growing. As strategists such as Haass put it, "Pakistan is much more important than Afghanistan". Losing nuclear-armed Pakistan to the jihadis is a recurring (if exaggerated) Pentagon nightmare.

All of these uncertainties, created, evolving or exacerbated on Obama's watch, are overshadowed by the greatest imponderable of all: when, how and if the US can bring itself to talk to the Taliban and its allies, as urged by Britain, Pakistan and other allies who believe a negotiated settlement is the only way out.

On this crucial subject, the Obama administration appears divided. Admiral Mike Mullen, chairman of the US joint chiefs of staff, insisted in Kabul this week that additional military pressure will turn the tide by year's end – Nato's stated target. But senior US officials and, for example Obama's regional envoy, Richard Holbrooke, appear more open to discussion. Meanwhile influential voices are lobbying for a leaner, slimmed down strategy.

"The next six months will be a crucial time for a thoughtful (but ground-based) reappraisal of our approach," said a senior former US government official. "We need to settle on the necessary but cost-effective level of effort for counterinsurgency, counterterrorism, capacity building, regional co-operation and restraint."

The war logs looked back over the last six years of the war. Looking forward, there seems little reason so far to be believe that lessons have been learned or that anything fundamental in the American approach has changed. But not to worry. Obama is having another policy review in December.