Twenty years after occupying Afghanistan, the US is leaving. Almost certainly the Taliban will return, probably immediately, to control the most important parts of the country, arms smuggling and narcotics will return to dominate the Afghani economy, and the country’s tribal-based political economy will again regulate social life.

To the assessment that says America’s occupation of Afghanistan was a colossal mistake, some retort that the US has achieved the primary objectives for which it had gone into Afghanistan in the first place: striking a painful blow against the Taliban and killing Osama bin Laden – basically exacting revenge after 9/11.

But the cost has been thousands of American lives, tens of thousands of Afghani lives, and a trillion dollars.

There are also costs in terms of acute questions regarding America’s standing in the world.

The first question concerns America’s positioning in Asia.

America’s presence in Afghanistan put its armed forces at Russia’s soft underbelly, arguably giving the US a strategic leverage against Russia. It served as a backing to America’s presence in the Gulf, which meant the availability of further force against Iran, in case that was needed. And it gave America the ability to observe and potentially intervene in arguably the most dangerous dispute in the continent: that between the two nuclear armed states, India and Pakistan.

But these advantages have become obsolete. Russia proved immune to any potential threat from Afghanistan (not surprising given Russia’s first hand experience in the country). America’s strategic interests in the Gulf are declining, which is one of the reasons why America seeks to alter its relationship with Iran from confrontation to containment and in some cases cooperation. And with regard to the India-Pakistan conflict, America understands that its presence at the border is neither helpful nor welcomed.

Now America’s primary question in its positioning in Asia is, what to do about China. So far the most widely accepted view within American decision making circles is that America must remain able to operate – including militarily - in the entire continent, including in China’s direct neighbourhood. On the other hand, China’s primary military objective now is to deter America from operating in that specific neighbourhood. These two contradictory objectives give rise to an important point of contention in the nascent America-China strategic confrontation.

The leads to the second question. For the past twenty years, beginning in Afghanistan, America has become used to operating against opponents that are by far weaker and less sophisticated and organised. In China however, America will find an opponent that’s almost its equal in many respects.

This brings to the fore two points about how America is perceived – internally and externally.

Internally, American strategists, military commanders, forces on the ground, and sections of the society know – at least sense – that two decades of fighting in Afghanistan did not lead to much. The situation is arguably worse than that concerning Vietnam fifty years ago. Then, in the late 1960s and early 1970s, large sections of the American public was either for or against the war. Vietnam was at the very centre of American domestic politics let alone foreign policy. In the past decade however, Afghanistan (and Iraq) were side concerns in American politics, hardly receiving serious attention in public life. Astonishingly, hardly receiving serious attention at key centres of American foreign policy thinking.

This is indeed a consequence of fighting wars against vastly inferior opponents in terms of power and resources. In such cases, the wars become campaigns, where “missions” get supposedly “completed” after the mediocre defences of the inferior opponents were destroyed. The politicians who never doubted the outcome of the campaigns move on. The public was never inspired or had any doubts about the eventual “victory”. The stakes were supposedly too low. And yet, the actual operations continue; many years pass; and with time, not only the campaigns recede from public attention; they also lose the meanings for which they were supposedly started in the first place.

This leads to disillusionment and potentially to loss of faith in the mechanics of political decision making. Questions such as: why did we fight? For which objectives? What has been achieved? How were these decisions taken? And why did we continue? lurk unanswered.

Externally, the absurdity of how these military campaigns took lives of their own and continued for many years without clear grand strategies behind them, undermine America’s standing and credibility. The problem is not about allies – who have understood, for many years now, the short term perspective and the theatrical nature of, and centrality of compromises in American politics. For many allies, these characteristics are essential features and outcomes of the diversity, openness, and dynamism inherent in the politics of a global empire based in a continent, and that has a democratic system of governing.

Opponents’ assessments are different, however. Many see these characteristics as serious vulnerabilities. In this view the US is already a modern version of the Roman Empire in decline – vast inequalities and social differences within, a centre drawn to its internal political squabbles hardly appreciating the major changes taking place round the empire, a military and a bureaucracy that look with disillusionment at the centre and have muted anger at what that centre imposes on them, and with all of that, the decision making mechanisms at the centre often lacks discipline, decisiveness, and crucially long term perspective – characteristics that these opponents strive to command and project.

Leaving Afghanistan ends a bizarre chapter in American foreign policy. But it underlines questions about American positioning in the world. Those questions were brushed aside when the US ruled supreme as the sole global super power. Today these questions are salient because the US is entering its most important strategic confrontation since the end of the Cold War, a confrontation that will affect almost all parts of the world.