The relevant change in the tax law was that miscellaneous unreimbursed employee expenses can no longer be itemized. In previous tax years, employees could use a Schedule A (where you itemize your mortgage, charitable contributions, etc) to also itemize unreimbursed expenses. This applied to most all employees with unreimbursed expenses like a traveling salesman for unreimbursed lodging. The expenses for Air Force folks were usually related to uniforms, and this is why Lt Snuffy would save all of his dry cleaning receipts. For 2018 going forward, employees can no longer itemize unreimbursed expenses on Schedule A.
But Reservists who travel more than 100 miles from home to perform military duty can/should file Form 2106 for their unreimbursed expenses related to traveling. This Form existed before 2018, and there don't appear to be any major changes to the Form. Form 2106 is an "above the line" deduction that helps lower your AGI and can be used even if you do not itemize other expenses on a Schedule A.