President Donald Trump on Thursday said that United States troop levels in Afghanistan will drop to 8,600 if a deal is reached with the Afghan Taliban and that a permanent presence will remain.

"We're going down to 8,600 and then we make a determination from there," Trump said in an interview with Fox News radio. “We're always going to have a presence."

Trump also said that if another attack on the US originated from Afghanistan “we would come back with a force like [...] never before.”

US troops were first sent to Afghanistan after the September 11, 2001 terrorist attacks on US soil carried out by Al Qaeda, which was sheltered by the former Afghan Taliban regime.

Washington now wants to end its military involvement and has been talking to the Afghan Taliban since at least 2018.

Trump says that troops will only be reduced when the Afghan Taliban give a guarantee that its territory will not be used by Al Qaeda or other international militant groups.

Trump underlined that there was to be no complete withdrawal, keeping a force that would provide "high intelligence".

“You have to keep a presence,” he said.