Is X- Men First Class a prequel or reboot?

I was wondering if the new x-men movie is a sequel or a reboot. It seemed like a prequel because first they had scenes from the original trilogy in the trailer. Also the First scene of the new movie had the same scene as the first scene of the first movie in the trilogy. Third there were cameos of characters of the original trilogy. At the same time, they had Maura as a CIA agent but in the trilogy she is a teacher/scientist and also in the end of the new movie Xavier is paralyzed but in X-Men Wolverine which takes place in the 1970s he is still able to walk.