  In this paper we study K3 compactification of ten-dimensional massive type
IIA theory with all possible Ramond-Ramond background fluxes turned on. The
resulting six-dimensional theory is a new massive (gauged) supergravity with an
action that is manifestly invariant under an O(4,20) / (O(4) times O(20))
duality symmetry. We discover that this six-dimensional theory interpolates
between vacua of ten-dimensional massive IIA supergravity and vacua of massless
IIA supergravity with appropriate background fluxes turned on. This in turn
suggests a new 11-dimensional interpretation for the massive type IIA theory.
