As the last U.S. military plane took off from Kabul's international airport on August 30, 20 years after a U.S.-led invasion of the country. 

A U.S. Central Command announced the completion of the troops withdrawal from Afghanistan and the end of the mission to evacuate American citizens, third-country nationals and Afghans during a news conference held by the Department of Defense on Tuesday.

Since August 14, the day before the Taliban regained control of Kabul, the capital of Afghanistan, the U.S. and its NATO allies had hurried to evacuate as many people from Afghanistan as possible before the pre-set deadline of August 31, by U.S. President Joe Biden.

Read more: Live updates: U.S. completes withdrawal from Afghanistan

The combined effort has taken more than 122,000 people out of Kabul airport, according to the White House, amounting to one of the largest airlifts in history. Non-NATO countries also helped to evacuate tens of thousands of people during the final stage.

Qatar, which hosts the largest U.S. military base in the Middle East, has helped evacuate more than 40,000 people to Doha and will continue to facilitate international efforts in "the coming days," the country's ministry said in a statement on Thursday.

Meanwhile, the United Arab Emirates has helped to evacuate 36,500 people to date, including 8,500 who entered the country via its national carriers or airports, according to Reuters.

Other neighboring countries, including Pakistan and India, also helped with the evacuations through air and land routes.

Although a small number of foreign citizens remained in Afghanistan for various reasons, the Taliban have announced to allow all foreign nationals and Afghan citizens with travel authorization from another country to leave the country, according to a joint statement issued by Britain, the United States and other countries.

"We have received assurances from the Taliban that all foreign nationals and any Afghan citizen with travel authorization from our countries will be allowed to proceed in a safe and orderly manner to points of departure and travel outside the country," they said in the statement.

Countries, including Australia, Japan, France and Spain, would continue to issue travel documents to designated Afghans, it said.

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