About a third of U.S. military service members eligible to receive a COVID-19 vaccine have refused to be inoculated, the Pentagon said Thursday, with about a million vaccines so far provided to service members.

The number of servicemen that have so far refused to get vaccinated was detailed during a Congressional hearing this week. The U.S. Defense Department has yet to make the inoculations mandatory, citing that the vaccines have yet to receive full approval from the Federal Drug Administration.

During the hearing, Major General Jeff Taliaferro told officials that the figure is still based on "very early data," which could change as the vaccination campaign continues.

For most vaccines, the Pentagon makes it mandatory for all service members to get inoculated. Since the COVID-19 vaccines were only approved on an emergency basis, the Pentagon found it unethical to force their usage.

"There is a real limit, legally, that we have, to make it mandatory for our troops and their families," Kirby said.

A senior military medical officer however said that once the vaccines get full approval from the FDA, all service members will be required to take the vaccine.

Pentagon Spokesman John Kirby said that the defense department has so far administered 916,500 vaccines. Kirby pointed out that the rate of refusals within the military mirrors that of the general population.

"We in the military basically mirror the acceptance rates of American society," Kirby said, adding that he had already taken the vaccine and has encouraged military service members to do their own research and to consult their doctors to ease their concerns.