US Defense Secretary Jim Mattis resigned Thursday, leading a chorus of protests at home and abroad after President Donald Trump ordered a complete troop pullout from Syria and a significant withdrawal from Afghanistan.

US Defense Secretary Jim Mattis has visited Kabul to pledge support for the government of President Ashraf Ghani, with the precarious security in the Afghan capital underlined by a rocket attack on the airport hours after he touched down.

US Defense Secretary Jim Mattis arrived in Afghanistan on an unannounced visit Monday, an American defence official confirmed, hours after his Afghan counterpart resigned over a deadly Taliban attack.