After talks in Doha, Khalilzad will travel to Kabul where he "will consult with the leadership of the Afghan government on the peace process and encourage full preparation for intra-Afghan negotiations," the department said.
An Afghanistan peace agreement that the US seems close to reaching with the Taliban has prompted worries that President Donald Trump's desire to quickly withdraw US troops could further plunge the country into civil war.
Trump said Friday he was pleased with talks on ending the war, 18 years after the September 11, attacks that prompted the US invasion of Afghanistan in the first place.
In recent days several US officials have suggested that an accord could be imminent in discussions with the Taliban in Qatar.
The US negotiator, Zalmay Khalilzad, was expected to return to the region very soon in hopes of sealing an agreement with the Afghan rebel force.
Such a potentially historic accord has raised an outcry from an eclectic assortment of critics in Washington, ranging from neo-conservatives to former Democratic administration officials to ex-military heroes.
In tweets, interviews and op-ed pieces in newspapers, they are cautioning against hastily bringing home the 14,000 US troops in Afghanistan, a warning which some hope will also score points ahead of next year's presidential election.
And they are calling on Trump to treat this war as he did North Korea and its nuclear weapons and insist on no deal rather than a bad deal.
"Under no circumstances should the Trump administration repeat the mistake its predecessor made in Iraq and agree to a total withdrawal of combat forces from Afghanistan," retired general David Petraeus, who used to command those soldiers, warned in a piece for The Wall Street Journal.
He was referring to Barack Obama and how the withdrawal of US forces from Iraq helped fuel the emergence of the Islamic State group.
The main points of the peace accord being negotiated with the Taliban are known - US soldiers would withdraw in exchange for a pledge from them not to let Al-Qaida or the Islamic State group operate in the territory that the Taliban controls.
There would also be an immediate ceasefire, and the Taliban would begin talks with the Afghan government, with which the rebels have until now refused all dialogue.
After talks in Doha, Khalilzad will travel to Kabul where he 'will consult with the leadership of the Afghan government on the peace process and encourage full preparation for intra-Afghan negotiations,' the department said.