Taliban capture Kandahar, Afghanistan's second-largest city

The Taliban have captured Kandahar, the birthplace of their movement and the second-largest city in Afghanistan, the AP reports.

Why it matters: It's the 12th provincial capital overrun by the Taliban in about a week, delivering a hugely important strategic and symbolic victory for the insurgents.

The big picture: The Taliban first seized Kandahar in the 1990s before toppling the Afghan government in Kabul and declaring an Islamic state.

• They were driven out of the city of 600,000, also the birthplace of the group's founder, during the U.S.-led invasion of Afghanistan in 2001.
• Kandahar Airfield was one of the main bases housing U.S. and NATO forces — including more than 26,000 troops at its peak — before it was handed over to Afghan security forces in May, according to NBC News.

Driving the news: The Taliban captured Kandahar on the same day that they took Herat, the third-largest city in Afghanistan, and Ghazni, the closest provincial capital to Kabul.

• The U.S. Embassy in Kabul issued its second security alert in five days on Thursday, urging U.S. citizens to leave Afghanistan "immediately."
• U.S. intelligence officials now believe Kabul could fall to the Taliban within 30 to 90 days — a stark revision from a previous assessment that the city could possibly fall six to 12 months after the U.S. military's full withdrawal.
• The New York Times reported on Thursday that U.S. envoy Zalmay Khalilzad is seeking to convince Taliban leaders that the U.S. embassy "must remain open, and secure, if the group hopes to receive American financial aid and other assistance as part of a future Afghan government."

Behind the scenes: The Taliban have stunned even some seasoned military and national security officials in the U.S. government with the speed of its conquests over the past week, as Axios reported on Wednesday.

• Even so, President Biden isn't budging — he is resolved to get out by Aug. 31, no matter what.
• "I do not regret my decision," Biden told reporters Tuesday. "We spent over a trillion dollars, over 20 years. We trained and equipped with modern equipment over 300,000 Afghan forces. ... They've got to fight for themselves."

Go deeper: Inside the Biden administration as Afghanistan collapses