Overview of what has happened per Washington Post. What stands out for me is that the Taliban were shocked at how easy it was to invade Kabul.
"A spur-of-the-moment decision by the president to escape the country, based on apparently incorrect information supplied by his advisers, was the most consequential. Later, the United States had one last chance to challenge Taliban supremacy in Kabul but opted to focus squarely on getting its people out from the airport.
This account of Kabul’s fall — the climactic moment of America’s longest war — is based on nearly two dozen interviews with U.S. and Afghan officials, a Taliban commander and residents of the city.
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In June, U.S. intelligence agencies had assessed that the Afghan government would hang on for at least another six months. By August, the dominant view was that the Taliban wasn’t likely to pose a serious threat to Kabul until late fall.
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In a July meeting with Ghani in Kabul, [Marine Gen. Kenneth “Frank” McKenzie, head of U.S. Central Command, and Ambassador Ross Wilson] told the Afghan president that his team needed a “realistic, implementable and widely supported plan to defend the country” and must drop the idea of defending all 34 provincial capitals, said an official familiar with the meeting.
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McKenzie, aware of those orders, told Baradar that the U.S. mission was only to evacuate American citizens, Afghan allies and others at risk. The United States, he told Baradar, needed the airport to do that.
On the spot, an understanding was reached, according to two other U.S. officials: The United States could have the airport until Aug. 31. But the Taliban would control the city.
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At the State Department, top brass, including Wendy Sherman, Blinken’s deputy, and Victoria Nuland, undersecretary of state for political affairs, were frantically calling foreign ministers to ask them to help with evacuation efforts and to coordinate a statement signed by 114 countries urging the Taliban to allow safe passage for evacuees. This, they realized, would be a historic evacuation effort.
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