US peace envoy Zalmay Khalilzad said on Tuesday he still believes peace is possible in Afghanistan and that keeping US forces in the country did not make sense.

Testifying before Congress, Khalilzad said: “The choice that the Afghans face is between a negotiated political settlement or a long war.”

“That opportunity is once again confronting them and it’s up to them,” he said.

Leading members of Congress have offered mixed reactions to Biden’s announcement and Senate leaders said on Tuesday they are concerned Biden is rushing a US withdrawal.

“How we withdraw and what political arrangement is left in our wake matters deeply,” said Senator Bob Menendez, a Democrat who has been critical of the Biden administration’s handling of the decision.

“If the Taliban were to come back to power, the reality for Afghanistan’s women and girls, I think, would be devastating,” said Menendez.

When they ruled Afghanistan from 1996-2001 the Taliban forbade education for girls and largely kept women out of the workforce and public life in general.

Khalilzad said any future support of a government that included the Taliban would be conditional. “If they do want US assistance, they want international acceptance … those things will be all affected by how they treat their own citizens, first and foremost the women of Afghanistan, children and minorities,” he told the senators.

Senator Jim Risch, the senior Republican, said the US military withdrawal should proceed only with safeguards for the gains the US has made in Afghanistan.

“I have deep concerns about the administration’s rush for the exits in Afghanistan,” Risch said.

“I hope I’m wrong, but I’m concerned that the administration’s decision may result in a Taliban offensive that topples the government,” he said.

But Khalilzad said he did not think this would happen.

“I do not believe the government is going to collapse or the Taliban is going to take over,” Khalilzad said.

Khalilzad testified to Congress the same day the State Department advised US citizens “wishing to depart Afghanistan should leave as soon as possible” and ordered non-essential US embassy workers to leave the country, saying “travel to all areas of Afghanistan is unsafe”.