The Taliban sealed off large portions of the area around Kabul's airport on Saturday as the threat of more Islamic State attacks remained ahead of the impending withdrawal, AP reports.

Driving the news: The U.S. Embassy had warned American citizens late Friday that due to continued security threats, they should "avoid traveling to the airport and to avoid airport gates."

• "U.S. citizens who are at the Abbey gate, East gate, North gate or the New Ministry of Interior gate now should leave immediately," the notice warned.

The big picture: The U.S. carried out a retaliatory drone strike on Saturday local time in response to Thursday's Kabul airport attack.

• "The unmanned airstrike occurred in the Nangahar province of Afghanistan," Capt. Bill Urban, spokesman for the U.S. Central Command, said in a statement. "Initial indications are that we killed the target. We know of no civilian casualties."

Of note: The United Kingdom’s final flight for civilians also departed Saturday as the wind-down continued ahead of the Aug. 31 deadline.

• "It’s time to close this phase of the operation now," UK Ambassador Laurie Bristow said in a video message, “but we haven’t forgotten the people who still need to leave and will continue to do everything we can to help them.”

Go deeper: The Afghan refugee crisis is about to get much worse