(The Hill) – U.S. Army Secretary Christine Wormuth this week warned members of the National Guard that they may be barred from “continued service” if they refuse to get vaccinated against COVID-19.

“I have determined that all soldiers who refuse the mandatory vaccination order will be flagged,” Wormuth wrote in a memo, according to The New York Times. This action would prevent soldiers from receiving promotions, awards, and bonuses.

If members persist in declining vaccination without an approved exemption, she added, they will not be allowed to “continue service.”

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Wormuth’s warning comes amid a continued standoff with the Oklahoma National Guard. Newly appointed Adjutant General Army Brig. Gen. Thomas Mancino has maintained that no members of the Oklahoma National Guard will be required to get vaccinated.

Earlier this month, Oklahoma Gov. Kevin Stitt (R) asked Defense Secretary Lloyd Austin to suspend the vaccine mandate for members of the Oklahoma National Guard, stating in a letter that roughly 10 percent of the force “have not and do not plan” on getting vaccinated.

The Times noted that around 89 percent of airmen in the Oklahoma Guard are vaccinated, while only 40 percent of Army guardsmen can say the same.

On Wednesday, a Defense Department official reiterated the administration’s stance on the vaccine mandate for U.S troops. The official said Austin “can establish a medical readiness requirement that applies to members of the National Guard,” adding that failure to meet this readiness requirement “could jeopardize their status in the National Guard.”

“To defend this Nation, we need a healthy and ready force. After careful consultation with medical experts and military leadership, and with the support of the President, I have determined that mandatory vaccination against coronavirus disease 2019 (COVID-19) is necessary to protect the Force and defend the American people,” Austin wrote in an August memo.