Brigadier Max Marriner, a former commander of British forces in Iraq, said it is critical to ensure the departure is done as securely as possible.
Brigadier Marriner said: "We've got a resurgent Taliban; we've got a political situation that's not great.
"What you want is a structured, measured withdrawal which you do not leave any vacuums in, so that nothing can go into that vacuum you've created by your departure.
"If you're to achieve that, you need to have an awful lot of things in support of you, and that means bringing stuff into country to get you out of country – and by that, I mean boots, because you're going to make sure your security has got to be good.
"Or better than good, it's got to be squeaky."
Coalition forces have had a presence in Afghanistan since 2001, with British troops currently deployed in a training role as part of a NATO mission.
The US has announced it is aiming to completely withdraw its personnel from Afghanistan by 11 September - the 20th anniversary of the 9/11 terror attacks.
Under the Trump administration, Washington had agreed with the Taliban to withdraw all its troops from Afghanistan by 1 May 2021, but that was pushed back by President Joe Biden in April.
NATO followed suit and said it would begin removing military personnel from 1 May, with the aim of completing its drawdown "within a few months".
Last week, America sent additional troops and capabilities to the region to boost security for the withdrawal and earlier this week, handed over a facility to the Afghan National Army.
Similarly, old British bases will be handed over to Afghan security forces.
Brig Marriner said sorting the logistics is a complex task: "At the moment, you need to draw everything back onto a large facility that will allow you to get people in there, administered, sustained for a period of time, hopefully, the shortest period of time - you've got to feed them, you've got to water them, you've got to wash them, you've got to sleep them.
"These are really, really, really basic nerdy logistic issues, but if you don't address those, that's what going to make your plan go wrong.
"And then, of course, you bring in the unexpected and unknown equation which is 'what's the enemy going to do?'"
EU foreign ministers have been debating ways to maintain support for Afghanistan after an attack on a girls' school at the weekend underscored deep concern that violence will spread following the withdrawal.
Brig Marriner added: "When you are in a withdrawal, first and foremost, your three priorities are security, security and security."