Kabul

As Taliban races to take control of Afghanistan and the terrorist group literally on the doorstep of Kabul, the US embassy in the capital city of the war-torn country is scrambling to destroy its classified documents and evacuate American citizens.

Due to mounting offensive by the Taliban, the terrorist group has managed to get hold of half of the country's 34 provincial capitals and now control roughly two-thirds of Afghanistan, with complete pullback of foreign troops just two weeks away. The United States on Friday said it is "certainly concerned" by rapid the Taliban advances in Afghanistan, adding that the terror group is trying to isolate Kabul as they have "taken over border crossing, highways, and major intersections to control lines of communication and revenue".

As the security situation worsens in the country, 3,000 additional troops are en route to Afghanistan to assist with evacuation as the Taliban advances on Kabul.

During a press briefing, Pentagon press secretary John Kirby on Friday said Kabul is not right now an "imminent threat environment".

But Kirby added, "If you just look at what the Taliban's been doing, you can see that they are trying to isolate Kabul. Now what they want to do if they achieve that isolation I think only they can speak to."

Meanwhile, the Kabul embassy staff has begun destroying classified documents and equipment. An internal memo calls for the disposal of the American flag or items that could be used for propaganda purposes.

Back in Washington, the US State Department has begun preparing for a crisis, calling on volunteers with "High Threat, High Risk" and overseas experience for supporting US Embassy Kabul, The Washington Post reported citing a separate memo sent to staff.

Painting a grim picture of things to come in Afghanistan, one State Department official who works on security issues said that "the whole thing is about to go bad."