The former Tottenham and West Ham United striker is not one of the 23 players named by Roy Hodgson for the tournament, although he was selected for the standby list of seven the England manager will call upon if needed.
"It's hard even to find words to describe how I am feeling," Defoe declared. "I felt I had done enough. I feel sharper than ever and I have been on form and scored goals.
"To miss out, I feel devastated. I didn't really feel I had to sell myself to the manager.
"I had a situation at the 2012 Euros where I lost my dad and I had a decision to make. But I chose to go back out to Poland and Ukraine because I know how important it is to play for your country."
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