This week’s devastating Taliban attack on an Afghan military intelligence base was almost certainly designed to have an impact on talks the insurgents are having with US diplomats in Qatar.

The assault on the key post of the military’s National Directorate for Security (NDS) in the central Wardak province was a textbook insurgent operation that may have killed up to 100 intelligence personnel and trainee militiamen. Reports are still unclear but it seems that a massive bomb in a captured Humvee blasted a hole in the defensive wall before a handful of gunmen burst into the compound mowing down the startled and confused occupants. It is more than likely that the vehicle was able to reach the perimeter unchallenged because guards assumed it was friendly. Similar subterfuges have been used in previous devastating attacks.

Security failures or the presence of Taliban agents planted among the occupants of the base may have contributed to this latest serious debacle for the beleaguered government forces. But while commanders in Kabul may be trying to learn fresh lessons from this humiliation, the real take-home message from the assault is supposed to be heard thousands of miles away in the Trump White House.

The US military and some of its NATO allies are still on the ground in Afghanistan as advisers and trainers rather than front line combatants. There is a major intelligence operation directed against Taliban communications and senior commanders. The one fighting area where the Americans remain engaged is in the air with what are claimed to be precision bombing raids and attacks by unmanned drones. But deadly though these strikes certainly are, the reality is that ever since the first massive deployment of airpower in the Second World War, its only really effective application is in support of advancing ground forces. British and American carpet bombing of Germany killed around 600,000 people, mostly civilians, but not only failed to paralyze Nazi armaments production, but also did not manage, until the last few months of the bombing, to break the will of the population. Indeed, in the early stages of British “area bombing” of civilians in 1941, the raids actually boosted support for the Nazis and stiffened the popular will to resist.

Trump wants America out of its foreign entanglements. He is intent on finishing the withdrawals that his lackluster predecessor Barack Obama initiated. It is clear that the President’s disengagement in Syria is premature and goes against all good advice from his own people and loyal regional allies. But quitting Afghanistan and ending the longest military engagement in US history is an easier case to make, not least because this is a foreign policy failure that can in no way be laid at Trump’s door.

The nature of the continuing low-level Qatar talks between the US and the Afghan government and the Taliban, which began under Obama, is still unclear. It would be too much to hope that the Talibs are interested in power-sharing with President Ashraf Ghani. Their main demands must be that all foreign troops get out of the country and that US air strikes cease. What commitment is Trump demanding in return or is he quietly preparing to quit? If the latter, then this latest Taliban attack was obviously calculated to help him on his way.