In a now-viral video, the baby was seen being handed up to a waiting US Marine during chaotic evacuation scenes at Hamid Karzai International Airport.
The baby's family asked US troops to give medical care to their child, so the baby was treated at a hospital before being reunited with its father, Pentagon spokesperson John Kirby said at a Friday press briefing.
"I think this was a very humane act of compassion by the Marines," Kirby said.
The viral imagery prompted thousands of questions on social media about the child, its safety and the family's situation.
Watch: Former Royal Marine says UK And US responsible for 'absolute carnage' at Kabul airport.
Marine Corps spokesperson Major Jim Stenger told CBS News that the baby was "safe at the airport" in Afghanistan.
He added: "The baby seen in the video was taken to a medical treatment facility on-site and cared for by medical professionals.
"I can confirm the baby was reunited with [its] father and is safe at the airport".
Major Stenger did not provide any additional details, including how many children had been taken to similar treatment facilities in recent days.
A series of photos showing Marines playing with children at military checkpoints and giving children water has been released by the Department of Defense.
The Ministry of Defence (MOD) tweeted: "Our Armed Forces continue to work tirelessly at Kabul airport to ensure the safe evacuation of British nationals and Afghan civilians."
The department went on to add: "The UK Armed Forces have safely evacuated nearly 4,000 people from Afghanistan since 13 August."
Meanwhile, Defence Secretary Ben Wallace wrote in an article for the Mail on Sunday: "Soldiers trained for war are instead holding babies and co-ordinating crowds."
Another example of the unique situation troops are facing happened on board a US Air Force C-17 plane flying to Ramstein Air Base in Germany, where an Afghan woman gave birth, according to the US military.
The US military's Air Mobility Command tweeted that the mother began experiencing complications during the flight on Saturday.
The tweet said: "The aircraft commander decided to descend in altitude to increase air pressure in the aircraft, which helped stabilise and save the mother's life."
On arrival at Ramstein, US medical personnel boarded the plane and delivered the baby in the aircraft's cargo bay.
"The baby girl and mother were transported to a nearby medical facility and are in good condition," the military said.