What is the difference between whether a reasonable officer could have believed that the force used was reasonable under the circumstances?

as to whether a reasonable officer could have believed that the force used was reasonable under the circumstances, both focused on the objective reasonableness of the officer's conduct. We therefore stated that "`the inquiry as to whether officers are entitled to qualified immunity for the use of excessive force is the same as the inquiry on the merits of the excessive force claim.'" Id. at 968 (quoting Alexander v. County of Los Angeles, 64 F.3d 1315, 1322 (9th Cir.1995)). We held that a material issue of fact on the reasonableness of the officer's conduct necessitated a trial. Id. at 970.