President Donald Trump earlier announced that the United States would reduce its military presence in Afghanistan to around 4,000 by November.

The US will bring its troop levels in Afghanistan to less than 5,000 by November, US Defence Secretary Mark Esper confirmed on late Saturday.

"We're going down to a number less than 5,000", Esper said on Fox News.

Currently, the US has about 8,600 troops stationed in Afghanistan. Earlier in July, the Defence Department confirmed withdrawal from five bases in Afghanistan as part of the agreement with the Taliban that calls for a total drawdown within the next nine-and-a-half months.

US troops have been engaged in military operations in Afghanistan for 19 years since the tragic 9/11 attack, but with little success, having failed to either defeat the Taliban or establish peace in the country by any other means.

Limiting US foreign military involvement was one of the key campaign pledges made by Trump. The president vowed to end what he calls America's "endless wars", including in Afghanistan.