"A major troop withdrawal must be contingent on final peace," the nine former diplomats wrote on the website of the Atlantic Council, a think tank group on Tuesday. "The initial US drawdown should not go so far or so fast that the Taliban believe they can achieve military victory," reported Tolo news.
The nine envoys, including five former ambassadors to Kabul, a former special envoy to Afghanistan and a former deputy secretary of State, issued their warning a day after the US chief negotiator Zalmay Khalilzad said the US and the Taliban have agreed in principle on withdrawal of nearly 5,000 American troops from Afghanistan.
Khalilzad in an interview with Tolo news declined to say how long the rest of the roughly 14,000 US troops would stay in Afghanistan.
However, the US officials have repeatedly said that the pullout would be "conditions-based". The withdrawal of the 5,000 troops from five bases in 135 days will be followed by Taliban's commitment to preventing their decades-long ally, al Qaeda, or other extremists from using the country as a haven for new attacks.
Khalilzad had said that Trump should approve the draft before it can be signed.
The former envoys wrote that maintaining a major US troop presence would have "a critical influence on the chances for successful peace negotiations."
"It is not clear whether peace is possible. The Taliban have made no clear statements about the conditions they would accept for a peaceful settlement with their fellow Afghans, nor do they have a track record of working with other political forces," they said.
"There is an outcome far worse than the status quo, namely a return to the total civil war that consumed Afghanistan as badly as the war with the Russ and something that could follow a breakdown in negotiations if we remove too much support from the Afghan state," they wrote.
A new civil war "could prove catastrophic for the US national security" as it likely would see the Taliban maintain their alliance with al Qaeda and allow ISIS's growing local affiliate" to further expand, they said.
This follows criticism by Khalilzad of Afghanistan President Ashraf Ghani's approach on the formation of the negotiating team.
In July, State Minister for Peace Affairs Abdul Salam Rahimi had said that discussions have started on the formation of a 15-member negotiating team, which is expected to engage in talks with the Taliban.
Khalilzad, who recently wrapped up the ninth round of talks with the Taliban in Doha, criticised the Afghan government for not finalising the negotiating team and said the delay in this respect showed there was a lack of will in taking forward the peace process.
( With inputs from IANS )