  We revisit propagation of galactic cosmic rays (CRs) in light of recent
advances in CR diffusion theory in realistic interstellar turbulence. We use a
tested model of turbulence in which it has been shown that fast modes dominate
scattering of CRs. As a result, propagation becomes inhomogeneous and
environment dependent. By adopting the formalism of the nonlinear theory
developed by Yan & Lazarian, we calculate the diffusion of CRs
self-consistently from first principles. We assume a two- phase model for the
Galaxy to account for different damping mechanisms of the fast modes, and we
find that the energy dependence of the diffusion coefficient is mainly affected
by medium properties. We show that it gives a correct framework to interpret
some of the recent CR puzzles.
