Mike Tyson always punches back.

Late Thursday night, the former heavyweight champion drafted a response to an open-letter by USA Boxing president Dr. Charles F. Butler that accused Tyson of “undermining the next United States Olympic Boxing Team.”

Butler’s letter, released through the media on Tuesday, complained Tyson’s promotional company Iron Mike Productions was luring top amateurs to sign a professional contract for “a pittance of their future worth” if they boxed in the Olympics.

Tyson, who hadn’t previously spoken about the issue, didn’t pull any punches in his letter, a copy of which was obtained by The Post.

“I am most disappointed that you and USA Boxing could not afford me the courtesy and respect, not only as a former heavyweight champion, but a former amateur champion to contact me first instead of taking advantage of my name and company for publicity,” Tyson wrote. “Your organization never attempted to contact me directly to discuss this matter. Had you done so, perhaps you would have a better understanding of my love for amateur boxing and my commitment to protect fighters by giving them the best possible opportunities this business can offer.

Tyson also defended his company’s signing of Erickson Lubin of Florida, a top 152-pound Olympic prospect, who turned 18 on Tuesday. Tyson said the signing “was solely his decision and based on consultation and input from his advisors.”

The youngest heavyweight champion ever also pointed out he turned pro at age 18 and “had a very successful professional boxing career.”

“No one knows better than I the pitfalls of amateur and professional boxing,” Tyson added. “This is precisely why I am compelled to make Iron Mike Productions a transparent company. Our priority is the well-being of our fighters and to produce the most exciting fights we can and in the process uplift the sport of boxing.

“I love my country and I love the liberties living in a democracy affords. These young fighters have worked diligently and deserve the right to pursue the best path they deem fit for themselves. Unfortunately, many of them can’t wait around for a very slim shot at Olympic glory.”

Those closest to Tyson know of his love for the purity of amateur boxing. He missed being part of the decorated 1984 Olympic boxing team when he was beaten in a close decision at the Olympic Trials by Henry Tillman. That was the heyday of Olympic boxing. Since then, the program has produced few marketable champions.

“Our country hasn’t had a male boxing gold medalist since 2004 [Andre Ward], which could be why many young hopefuls decide to turn professional sooner,” Tyson wrote.

“Many of these boxers are like me in that they are from poverty stricken communities and boxing is their only way to a better life. They have obligations beyond your personal vision for them. No one has the right to question the path a fighter chooses in pursuit of their American dream.”

Tyson concluded his letter by offering his assistance.

“I will always be supportive of amateur boxing and will continue helping in any way possible,” he wrote. “My door is always open to assist the USA Boxing team reach its goals. Hopefully, in the future, you will be more comfortable reaching out to me directly.”