Former President Donald Trump launched on Saturday a sustained attack on President Joe Biden's handling of the retreat of US forces from Afghanistan, which he called "the greatest foreign policy humiliation" in US history.

Trump, a Republican who has dangled the possibility of running again for president in 2024, has repeatedly blamed Biden, a Democrat, for Afghanistan's fall to the Islamist Taliban, even though the US withdrawal that triggered the collapse was negotiated by his own administration.

"Biden’s botched exit from Afghanistan is...