  Charged pions produced in very high energy hadronic interactions might be the
dominant source of cosmic neutrinos in the GeV--TeV range. Spectral energy
power of \pi^+ radiation by high energy protons moving in strong magnetic
fields typical for magnetars is determined with a semiclassical treatment of
the effective pion-nucleon model. The main characteristics emerging from a
saddle point approximation to the summation over the allowed range of Landau
levels is a sharp lower cut: E_\pi>0.25 E_p. The magnitude of the spectral
power agrees in this region with the synchrotron radiation spectra of neutral
pions.
