transcendental numbers as solutions to hyperpowers

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By the Gelfond-Schneider theorem, if $x^x=2$, $x$ must be transcendental. What can be said of $x$ if $x^{x^x}=2$, $x^{x^{x^x}}=2$ etc.? Must it be transcendental? Of course, $2$ can be replaced by any algebraic number.
Henry Harry Lande M Sc