The Pentagon said on Monday that it will require service members to receive the COVID-19 vaccine now that the Pfizer vaccine has received full approval, The Associated Press reported.

Pentagon spokesman John Kirby said Defense Secretary Lloyd Austin is making good on his vow earlier this month to require the shots once the Food and Drug Administration approved the vaccine. He added that guidance is being developed and a timeline will be provided in the coming days.

In a memo dated August 9, Austin had said he’d seek the president’s approval to make the vaccine mandatory no later than mid-September, or immediately upon FDA licensure “whichever comes first.”

The Pentagon has said that the military has enough vaccines to meet the requirements. The shots would be mandated for active duty and National Guard troops. There are more than 1.3 million on active duty and close to 800,000 in the Guard and Reserve.

Kirby said the steps Monday to make the vaccine mandatory are an effort to ensure the safety of service members, according to AP.

Kirby added that the Pentagon decision is only for the Pfizer vaccine.

The announcement came hours after the US Food and Drug Administration granted its full approval to the Pfizer-BioNTech coronavirus vaccine.

Several coronavirus vaccines have been in use for nearly a year, including vaccines produced by the Pfiizer, Moderna, and Johnson & Johnson companies. The Pfizer vaccine is the first vaccine against the coronavirus to win full FDA approval.