The Taliban called on the Afghan people in a statement Thursday to "unite for Islamic governance," underscoring how the Islamist group still rejects democracy despite showing a reconciliatory stance toward its erstwhile enemies.

In a statement issued on the day Afghans celebrate their independence from British rule in 1919, the Taliban again proclaimed victory in their nearly two-decade battle to regain power, saying "the arrogant superpower United States was forced to withdraw due to the resistance."

Concerns about the incoming administration are deep-rooted, stemming from the memory of abuses committed by the group, its treatment of women and its harboring of terrorists when it previously ruled Afghanistan from 1996 to 2001.

Many Taliban soldiers could be seen guarding roads leading to Kabul's airport where thousands of desperate people, some fearing possible retaliation and others the return of strict Islamic rule, have converged in recent days in a bid to get on evacuation flights.

There have been cases where Afghans have been turned away by the Taliban despite having necessary certificates for travel.

In the eastern city of Jalalabad, it was reported Wednesday that Taliban soldiers fired at demonstrators over the raising of the national flag, killing some of them.

Waheedullah Hashimi, a senior member of the group, told Reuters in an interview that while many issues regarding how the Taliban would run Afghanistan have yet to be finalized, the country would not be a democracy.

"There will be no democratic system at all because it does not have any base in our country," he was quoted as saying. "We will not discuss what type of political system should we apply in Afghanistan because it is clear. It is shariah law and that is it."

Hashimi also told the news agency that Afghanistan may be governed by a ruling council headed by somebody akin to a president.

But he said Taliban supreme leader Haibatullah Akhundzada would likely remain in overall charge, playing a role above the head of the council.

The last time the Taliban were in power, then supreme leader Mullah Omar remained in the shadows and left the day-to-day running of the country to a council.

Abdul Ghani Baradar, who is one of the founding members of the group, is seen as a leading contender to head the ruling body.

The Taliban on Tuesday declared an "amnesty" across Afghanistan, pledged not to retaliate against anyone and urged women to join their government, saying their rights will be respected under Islamic law.

However, Nobel peace laureate Malala Yousafzai, the Pakistani activist who was shot in the head by Taliban gunmen in 2012 because she campaigned for girls' education, told the BBC in a recent interview that she and other female activists are still concerned for the safety of women under the Taliban's interpretation of Islamic law.

Meanwhile, U.S. President Joe Biden mentioned for the first time in an interview with ABC News on Wednesday that the Aug. 31 deadline for completing the withdrawal of U.S. troops could be extended.

"If there's American citizens left, we're gonna stay to get them all out," he said.

The number of Americans remaining in Afghanistan is estimated at 10,000 to 15,000, while the number of U.S.-aligned Afghan citizens, such as former government officials and interpreters who worked with the U.S. military, is 50,000 to 65,000, counting their families.

In order for everyone to evacuate by the end of August, Biden said, several thousands would have to leave the country per day.

"It depends on where we are and whether we can get -- ramp these numbers up to 5,000 to 7,000 a day coming out. If that's the case, they'll all be out," he said.

According to the White House, about 1,800 people were evacuated by U.S. military transport planes from Tuesday night through Wednesday -- far short of Biden's targeted daily number.