If my employer pre- approved my vacation (PTO) and a week prior to when my vacation takes place I submit my two weeks notice, can my employer deny my PTO?

Over 2 months ago I submitted a request to take off, using my PTO, from July 5th to July 7th. On June 19th, I was offered a position with another company. I did not know at the time I submitted my PTO request that I would be searching for another position. On June 21st, I notified my supervisors that I will be leaving the company. They told me that I needed to submit something in writing so on June 22nd I submitted a formal letter stating that I will be leaving the company and my last day will be on July 7, 2018. Then today, June 29th, I am notified by one of the supervisors that "I may not be allowed to use my PTO during the 2-week period". I am upset with my current employer because when I submitted my 2 weeks’ notice there was no notification that this will be a problem. I am in a bind because I'm supposed to start my new job on July 9, 2018. I feel my current employer has sideswiped me and are trying to take advantage of me. I have spoken with other past employees and current employees and they have all told me that this is the M.O. of the company. They try to screw their employees over. I don't think this is fair at all because I earned my PTO and the owner of the company has a reputation for not treating him employees well. For instance, if a family member dies you are forced to use your PTO instead of receiving bereavement. Not sure if this helps but I am also a US Air Force Veteran.