Trump congratulates Ashraf Ghani on Afghan peace process

US President Donald Trump has congratulated his Afghan counterpart Ashraf Ghani on the recent key steps taken towards achieving peace in the war-torn country, the White House has said.

After 18 years of war, the US and the Taliban signed the peace deal in Doha on Saturday to facilitate intra-Afghan dialogue in Oslo this month and the withdrawal of all foreign forces from Afghanistan in 14 months.

Trump and Ghani spoke over phone on Sunday, the White House said on Monday.

"The two leaders agreed that Saturday's announcement of the United States-Afghanistan Joint Declaration and the Agreement for Bringing Peace to Afghanistan were important milestones for the Afghan peace process," it said.

"They further agreed to stay in touch as the peace process moves into the next phase, which involves negotiations among Afghans for a comprehensive and permanent ceasefire and roadmap for the political future of the country," the White House said in a readout of the call.

Under the US-Taliban pact signed in Doha, the US has agreed to reduce its troops in Afghanistan from 13,000 to 8,600 in the next 130 days and withdraw all its soldiers in 14 months.