Editor’s note: This article by Stephen Losey originally appeared on Military.com, a leading source of news for the military and veteran community.

The U.S. military plans to begin flying hourly evacuation flights out of Kabul and hopes to move anywhere from 5,000 to 9,000 people each day, including Americans, Afghan refugees and other nations' citizens.

However it’s unclear whether those potential passengers will be able to get to the airport, as the Taliban have erected checkpoints throughout Kabul and are searching for Afghans who fought for the deposed government or assisted Americans over the two-decade conflict.

The evacuation plans underscore the scale of the historic emergency airlift operation and the daunting challenge facing the U.S. military as it seeks to mitigate the damage from the breathtaking collapse of Afghanistan and seizure of the country by the Taliban.

There are tens of thousands of Afghans -- perhaps as many as 100,000, including interpreters, refugees and family members -- who are desperate to escape the country, and only two weeks remaining to get them out before the military's planned conclusion to its two-decade Afghanistan mission Aug. 31.

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The 82nd Airborne Division from Fort Bragg, North Carolina, is in charge of securing Hamid Karzai International Airport in Kabul -- the last site in Afghanistan where U.S. troops maintain a presence. The 82nd specializes in securing and operating airfields in hostile areas. The U.S. also is conducting air traffic control at the Kabul airport.

By the end of Tuesday, there will be about 4,000 U.S. troops on the ground, Maj. Gen. Hank Taylor, deputy director for the Joint Staff for regional operations, told reporters Tuesday morning. That is up from about 2,500 troops as of Monday morning.

Military flights are ongoing, as well as limited civilian flights, he said. The airport was closed for several hours Monday after hundreds of desperate Afghans flooded the tarmac, leading to a shocking scene in which they mobbed a taxiing C-17. Some clung to it as it took off and fell to their deaths. Politico reported that the body of a dead Afghan was found in the C-17's wheel well after an emergency landing. The Air Force said it will release further information about the incident later Tuesday.

Taylor said the Afghans who rushed the airfield on the southern civilian side of the airport are no longer there.

Nine C-17 Globemaster III flights arrived at the airport overnight, bringing in equipment and about 1,000 troops. Seven C-17s also flew out, carrying a total of 700 to 800 passengers, including 165 American citizens, as well as Special Immigrant Visa, or SIV, applicants and other countries' citizens.

Defense One reported that a C-17 flight with the call sign Reach 871 packed 640 Afghans on board Sunday, nearly a record for the massive transport aircraft. An image of the crowd of people on board was captured in a photograph that went viral.

A U.S. Air Force C-17 Globemaster III safely transported approximately 640 Afghan citizens from Hamid Karzai International Airport on Aug. 15. (Courtesy photo via Air Force) 

The military's first priority was to deliver troops and equipment to the airport. But as the insertion of these service members is completed -- bringing the troop presence to roughly 6,000 -- Taylor said the speed of evacuations will increase.

While the military's goal is to evacuate up to 9,000 people daily, Taylor cautioned that the situation on the ground is shifting, and unexpected challenges could arise. He said he hoped to have one evacuation flight per hour, around the clock, within the next 24 hours.

"Airlift is not going to be a limiting factor," Pentagon Press Secretary John Kirby told reporters Tuesday.

The military is in talks with the Taliban; that includes U.S. commanders at the airport talking to Taliban commanders outside the facility, Kirby said. But Taylor said the group now in control of the country has not threatened, attacked or had any recent hostile interactions with the U.S. military.

Pentagon officials did not answer questions about whether talks with the Taliban include procedures to allow Americans or Afghans to reach the airport or expanding the perimeter around it to allow more room to operate safely.

[MORE AFGHANISTAN NEWS: Military Times | Military.com]

U.S. troops on Monday shot and killed two people at the airport who were allegedly armed and hostile. But the Pentagon later said it had no indication the individuals were with the Taliban.

Kirby said the military still plans to conclude all missions in Afghanistan by Aug. 31; he would not speculate what might happen beyond that date if evacuations aren't complete.

The military is working "hand in glove" with the State Department to process Afghans seeking to escape, Kirby said, including those who worked for the U.S. in interpreter or other jobs, and other refugees. There were recently 18,000 SIV applicants still awaiting their visas to be processed. Including their immediate family members, there are at least 70,000 Afghans who need to be evacuated, advocates estimate. And with other potential refugees, that could mean the military has two weeks to evacuate about 100,000 people -- a daunting task.

About 500 to 600 Afghan soldiers from the now-defunct Afghan National Defense and Security Forces are at the airport helping with security, Taylor said.

When asked whether the U.S. would bring those Afghan troops to the United States, Kirby said they must decide for themselves if they want to leave and would have to apply for visas.