More than 8,700 military personnel were discharged for refusing to comply with the mandate, which was lifted in January 2023, but figures are not available for those who left by choice.

"The back pay calculation would look at the pay and entitlements they would have received," Pentagon official Tim Dill told reporters.

"That would include things like base pay, allowance for housing, allowance for subsistence, and it could also include medical benefits."

The mandate was put in place during the pandemic to help protect troops from the disease but was lifted at the demand of Republican lawmakers.

Republicans insisted Covid-19 prevention measures infringed on personal freedom and threatened to hold up the 2023 defense spending bill if it did not require an end to the mandate, but a proposal for back pay was not included in the legislation.