Even as the administration of US President Donald Trump is reviewing its Afghan policy, the Taliban has written an open letter to Trump urging full withdrawal of American forces from the conflict-torn country. The Islamist group has stepped up its insurgency in recent months capturing vast swathes of territory.

Dated 15 August and written in English, the letter was circulated to journalists through regular jihadist channels by Taliban spokesman Zabihullah Mujahid. The group demanded that US forces leave the country altogether after 16 years of bloody conflict instead of increasing the number of troops.

"Previous experiences have shown that sending more troops to Afghanistan will not result in anything other than further destruction of American military and economic might," the Taliban said in its 1,600-word letter which adopted a negotiating tone. It called on Trump to "generously" hold a dialogue with the Afghans rather than choosing war.

"It seems to be a historical mistake on part of the previous administrations to have dispatched American youth for the slaughter of Afghans. However, as a responsible American president, you need to study the mistakes of your predecessors and prevent death and injury to American forces in Afghanistan," added the open letter.

With more than $100bn spent since the US' first invasion in 2001, Afghanistan has been regarded as Washington's costliest conflict so far. Attributing the ongoing violence in Afghanistan to the "occupying forces" of the US, the Taliban said US presence only fuels the fighting in the country.

"A number of warmongering congressmen and generals in Afghanistan are pressing you to protract the war in Afghanistan because they seek to preserve their military privileges, but instead you must act responsibly as the fate of many Americans and Afghans alike is tied to this issue," the Taliban said.

The letter comes a day after US Defence Secretary James Mattis said the Trump administration was considering all options on Afghanistan. He also revealed that a full withdrawal of US troops from Afghanistan was being considered.

Afghanistan Taliban attack
A member of Afghanistan's special forces point his gun as he observes the enemy lines in Achin district of Nangarhar province in eastern Afghanistan Parwiz Parwiz/Reuters