How long does it take for the US military to admit defeat? The answer is forever, according to Harlan Ullman. Today there are US soldiers deployed in Afghanistan who were one year-olds when the war began. Yet the Taliban is no closer to being banished than it was in 2001. Indeed, it occupies considerably more of the country today than it did two years ago. In the meantime, the US presence has fluctuated from a few thousand troops to more than 100,000 and back again. Each president thinks he has found the key to winning the conflict. Every time, the key breaks. Yet the Pentagon refrain continues: “Give me the tools and I will finish the job.

If there was a president who might have resisted the “deep state” it was Donald Trump. He campaigned against America’s endless wars in Iraq, Afghanistan and elsewhere. He won the mandate to say “no” to the Pentagon. Yet, in power, Mr Trump has given the Pentagon everything it has requested — and more. For the first time in modern US history, military commanders have discretion to make large battlefield decisions without civilian approval.

Last year, the Pentagon took advantage of its new latitude to drop the “mother of all bombs” — the largest non-nuclear weapon in history — on an Isis-occupied warren of caves in eastern Afghanistan. “We have the greatest military in the world,” said Mr Trump. “We have given them total authorisation and that is what they are doing.” Alas, Isis is still there.