Reading over the text of Trump’s Afghanistan speech, I was struck by his easy acceptance of the conventional hawkish view that withdrawal from Iraq in 2011 was a mistake that shouldn’t be repeated elsewhere:
And, as we know, in 2011, America hastily and mistakenly withdrew from Iraq. As a result, our hard-won gains slipped back into the hands of terrorist enemies. Our soldiers watched as cities they had fought for, and bled to liberate, and won, were occupied by a terrorist group called ISIS. The vacuum we created by leaving too soon gave safe haven for ISIS to spread, to grow, recruit, and launch attacks. We cannot repeat in Afghanistan the mistake our leaders made in Iraq.
This convenient bit of revisionism omits several important things. First, most Iraqis didn’t want a continued U.S. presence in Iraq. Second, the U.S. could not secure a new Stats of Forces Agreement that gave American forces legal immunity, and it was politically impossible for Iraqi leaders to agree to such a condition after eight years of occupation. Finally, a U.S. residual force would not have been enough to stop any of the things that happened in the years that followed, and their presence would have very likely triggered a new insurgency against them. Withdrawing from Iraq wasn’t a mistake. It was a necessary first step in extricating the U.S. from its entanglements in the region.
Unless the U.S. intends to make Afghanistan its permanent ward and wishes to be at war there forever, there is no compelling reason for a continued American military presence. Nothing in Trump’s speech provided such a reason. He embraced the sunk cost fallacy (“our nation must seek an honorable and enduring outcome worthy of the tremendous sacrifices that have been made”), and ignored that throwing away more lives on a failed war is far worse than cutting our losses. He indulged the safe haven myth, according to which the U.S. must police countries on the other side of the earth without end for fear that they might give shelter to terrorists if we do not. These are all very familiar and cliched assumptions by now, and they are wrong. We can’t rationally weigh costs and benefits of a war that can’t end unless it somehow redeems the losses already suffered, and Afghanistan is never going to be made secure enough at an acceptable cost to eliminate the possibility that some part of its territory might play host to jihadists. Trump calls his approach “principled realism,” but as usual it is neither principled nor realist.
Trump defined the mission as “killing terrorists,” which practically guarantees that more terrorists will be created in the process and ensures that the mission will never end. There have been higher numbers of civilian casualties in Iraq and Syria since Trump took office, and Trump’s statement that he “lifted restrictions the previous administration placed on our warfighters” promises that the same will happen in Afghanistan. He also made a rather alarming statement, saying “that no place is beyond the reach of American might and Americans arms.” That reflects a potentially very dangerous contempt for the sovereignty of other states that could easily blow up in our faces.
Trump typically dressed up his lack of a discernible strategy as a cunning ruse: “America’s enemies must never know our plans or believe they can wait us out.” 
Of course, people living in their own part of the world can always “wait us out.” It is the height of hubris and stupidity to think we can outlast them. His assertion that the U.S. will integrate “all instruments of American power — diplomatic, economic, and military — toward a successful outcome” isn’t credible when his administration is presiding over the gutting and wrecking of the State Department.
Trump defined victory as “attacking our enemies, obliterating ISIS, crushing al-Qaeda, preventing the Taliban from taking over Afghanistan, and stopping mass terror attacks against America before they emerge.” Based on this definition, victory is not possible at an acceptable cost. The preoccupation with “winning” an unwinnable war just dooms the U.S. to fight there for decades to come. If we can’t admit failure after sixteen years of it, when will we?

http://www.theamericanconservative.com/larison/trumps-awful-afghanistan-speech/