The Vlasov kinetic equation for plasma that is usually treated as arncollisionless approximation is shown to satisfy the complete BBGKY hierarchyrnafter some modification of the latter, thus being an exact solution of it.rnBased on the perturbation method originated from this exact solution, linearizedrnequations for averaged deflections of plasma particles from their unperturbedrnself-consistent trajectories are derived to be used for therninvestigation of plasma waves. Instead of the Maxwell equations for electromagneticrnfields their solutions in the Lienard-Wiechert form are used. Allrnthe known results of the ordinary linear theory of plasma oscillations andrnwaves are shown to be reproducable in this approach, but in addition, smallrncorrections of the first order in the plasma parameter due to the Debyernscreening are obtained. A simple consideration of a rarefied plasma in arnstrong magnetic field is given indicating the possibility of a non-cyclotronrncharacter of the motion of the particles that may be important for the plasmarnconfinements in magnetic traps