Can I be fired due to my VA disability?

Hi, My fiancé recently was approved for 70% VA disability. He has been working at a job that requires him to lift heavy objects which required a physical prior to being employed which he passed. He has been at the job for 1 year now and recently was approved for the VA disability. Upon informing his employer of this they now want to send him for a physical once again to potentially try and let him go from his job. He has done the job without any accommodations for a year and was trying to keep them informed. Under the American Disability Act is this illegal. He works in Idaho but the headquarters are in Puyallup, WA. Thank you.