"I strongly support (Defense) Secretary (Lloyd) Austin's message to the Force today on the Department of Defense's plan to add the COVID-19 vaccine to the list of required vaccinations for our service members not later than mid-September," Biden said in a statement released by the White House on Monday hours after the DOD unveiled Secretary Austin's memo. 

Earlier in the day, Austin said in the memo that he "will seek the president's approval to make the vaccines mandatory no later than mid-September, or immediately upon" licensure by the US Food and Drug Administration (FDA), "whichever comes first". 

Absent the FDA's full approval to the Pfizer vaccine, which is now authorised only for emergency use, Austin will have to seek a waiver from Biden in order to make inoculation compulsory for the men and women in uniform. 

The Secretary said in the memo that a full FDA licensure is expected "early next month". 

The Pentagon's decision came a little over a week after Biden announced that he had directed the department "to look into how and when they will add Covid-19 to the list of vaccinations our armed forces must get". 

Discussions over mandatory vaccination among active duty troops gained momentum after Biden, while making the suggestion to the Pentagon, announced in late July that all federal civilian workforce in the executive branch were required to attest to their vaccination status, or subject to regular testing, mask-wearing and social-distancing while on the job, as well as restrictions on official travel. 

According to Pentagon data, more than 1 million troops have been fully vaccinated and another 237,082 have received one shot. 

The data also showed that vaccination rates vary widely among different military services.