"With the departure of our military and those of the many partners who stood with us, Afghans face a moment of decision and opportunity," Khalilzad said via Twitter on Monday. "Their country's future is in their hands. They will choose their path in full sovereignty. This is the chance to bring their war to an end as well."
The last US flight left Kabul airport at 3:29 EST, marking the end of the United States' 20-year war in Afghanistan and leaving the Taliban* with full control of the entire country.
Khalilzad said the Taliban face a test on whether it can lead Afghanistan to a prosperous future.
In 2019, former Afghan national security adviser Hamdullah Mohib accused the Trump administration of trying to unseat former Afghan President Ashraf Ghani and replace him with Khalilzad.
The Taliban completed their takeover of Afghanistan by entering Kabul on August 15, which led to the collapse of the US-backed civilian government. Following those events, most countries started evacuating their citizens and diplomatic staff, as well as Afghan allies.
Washington has admitted its security services' failure to thwart the terrorist attacks amid a chaotic US evacuation from Afghanistan. The White House confirmed that President Joe Biden gave the US military all the authority needed to carry out attacks against Daesh*-Khorasan without congressional approval.
*Terrorist organizations banned in Russia and many other states