There have been exceptions granted in the past, though, including special clearance given to former Navy fullback Eric Kettani, which allowed him to play in the NFL.
"Ultimately, it's whatever the Navy wants to do with me and I'm ready and willing to do whatever they ask," Cardona said during the NFL scouting combine."It's something that I'm definitely looking into applying for. All that comes down to the needs of the Navy and what they foresee me doing and how they want me to serve, what they see serving the country."
The Navy gave Cardona a special dispensation to play in the Senior Bowl and clearance to participate in the scouting combine.
If Cardona isn't allowed to play immediately in the NFL, he says he doesn't view that as a negative. Cardona will graduate as a Marine in May and then head to The Basic School at Quantico.
"I don't see any downside to it," Cardona said. "It's a guaranteed job and a career that a lot of people really aspire to be. It's a really honorable thing to be, to be a Naval officer. I look forward to whatever I do the next two years, whether it's in the NFL or leading sailors and Marines. I'm excited for whatever comes next. Getting the opportunity to play football is a dream come true and I hope it comes to fruition."