The Taliban has warned President Donald Trump to reverse US policy on Afghanistan or face a "historically shameful defeat", a US-based monitoring group reported Sunday. 

An article, which the SITE Intelligence Group said appeared on the Taliban's website and social media, described the freshly inaugurated leader of the free world as "an enigma both to the Americans and the billions of people around the world".

The article said that Afghans hoped Trump and his cabinet would not follow in the footsteps of previous White House administrations. Afghanistan, which the US invaded on October 7, 2001, has become Washington's longest military intervention since Vietnam. It has also been the most costly, with more than $100 billion (93 billion euros) spent. But the country remains wracked by insecurity as the resurgent Taliban dealt Afghan forces serious blows in 2015, the first year they led security operations in Afghanistan, taking over from Nato.

"Even though America has never waged a war so long and passionately intense in its entire history but if she insists on continuing her failed arrogant policies, one can foresee that she will ruin herself beyond repair due to a historically shameful defeat," the article said.

Trump has yet to make an official pronouncement about US policy in Afghanistan, but the Taliban threat forced his predecessor Barack Obama to slow plans for a drawdown in US troop numbers. Some 8,400 will remain in the war-torn country this year, compared with 5,500 initially planned.

-AFP