  We examine the behavior of the leading Regge trajectory of the open bosonic
string in a uniform electromagnetic background and present a consistent set of
Fierz-Pauli conditions for these symmetric tensors that generalizes the
Argyres-Nappi spin-2 result. These equations indicate that String Theory does
bypass the Velo-Zwanziger problem, i.e. the loss of causality experienced by a
massive high-spin field minimally coupled to electromagnetism. Moreover, we
provide some evidence that only the first Regge trajectory can be described in
isolation and show that the open-string spectrum is free of ghosts in weak
constant backgrounds. Finally, we comment on the roles of the critical
dimension and of the gyromagnetic ratio.
