  We analyze the resolution of the U(1)_A problem in the Sakai-Sugimoto
holographic dual of large N_c QCD at finite temperature. It has been shown that
in the confining phase the axial symmetry is broken at order 1/N_c, in
agreement with the ideas of Witten and Veneziano. We show that in the
deconfined phase the axial symmetry remains unbroken to all orders in 1/N_c. In
this case the breaking is due to instantons which are described by spacelike
D0-branes, in agreement with 'tHooft's resolution. The holographic dual of the
symmetry breaking fermion condensate is a state of spacelike strings between
the D0-brane and the flavor D8-branes, which result from a spacelike version of
the string creation effect. In the intermediate phase of deconfinement with
broken chiral symmetry the instanton gas approximation is possibly regulated in
the IR, which would imply an eta' mass-squared of order exp(-N_c).
