  We consider linear stability of steady states of 1(1/2) and 3D Vlasov-Maxwell
systems for collisionless plasmas. The linearized systems can be written as
separable Hamiltonian systems with constraints. By using a general theory for
separable Hamiltonian systems, we recover the sharp linear stability criteria
obtained previously by different approaches. Moreover, we obtain the
exponential trichotomy estimates for the linearized Vlasov-Maxwell systems in
both relativistic and nonrelativistic cases.
