The Pentagon will make the COVID-19 vaccines mandatory for service members by mid-September, Defense Secretary Lloyd Austin said Aug. 9 in a memo to the force.

Shots could be required sooner if the vaccines receive full approval from the Food and Drug Administration, according to the memo.

Austin’s decision comes after President Joe Biden asked the military to consider how and when it could add the COVID-19 vaccines to the list of vaccinations required for all troops. He also “consulted closely” with senior military leaders, the service secretaries and chiefs and medical personnel, Austin said.

“Based on these consultations and on additional discussions with leaders of the White House COVID Task Force, I want you to know that I will seek the President's approval to make the vaccines mandatory no later than mid-September, or immediately upon the U.S. Food and Drug Agency (FDA) licensure, whichever comes first,” the memo states.

In a statement, Biden expressed his strong support for Austin’s decision. “Secretary Austin and I share an unshakable commitment to making sure our troops have every tool they need to do their jobs as safely as possible,” Biden said. “These vaccines will save lives. Period. They are safe. They are effective.”

More than 350 million shots have been administered in the U.S. alone, Biden said, as he emphasized the importance of continuing to battle COVID-19 and the delta variant.

“We are still on a wartime footing, and every American who is eligible should take immediate steps to get vaccinated right away,” he said. “I am proud that our military women and men will continue to help lead the charge in the fight against this pandemic, as they so often do, by setting the example of keeping their fellow Americans safe.”

The military will now begin preparing for this transition, Austin said.

“I have every confidence that Service leadership and your commanders will implement this new vaccination program with professionalism, skill, and compassion,” he said. “We will have more to say about this as implementation plans are fully developed.”

Unvaccinated federal personnel—uniformed or civilian—will continue to abide by restrictions and requirements for distancing and testing, the memo states.

“We will also be keeping a close eye on infection rates—which are on the rise now due to the Delta variant—and the impact these rates might have on our readiness,” Austin said. “I will not hesitate to act sooner or recommend a different course to the President if l feel the need to do so.”

The nation needs a “healthy and ready force,” Austin said. “I strongly encourage all DoD military and civilian personnel—as well as contractor personnel—to get vaccinated now and for military Service members to not wait for the mandate.”

Austin’s memo is available here.