Much like the federal government, which has enacted the Uniformed Services Employment and Reemployment Rights Act (USERRA), many states have enacted laws to protect the employment status of the men and women who serve in the armed forces (38 USC 4301et seq.).
Oklahoma has enacted such a law.
Remember that USERRA, a federal law, preempts any state law that is less protective of the employment and reemployment rights of uniformed service people. That is, if Oklahoma law is less protective than USERRA, the rights given by USERRA will apply and not the less protective Oklahoma law. In addition, if Oklahoma law is more protective than USERRA, the Oklahoma law will apply.