according to the deferential principles of Chevron and whether the agency’s regulation was ultimately acceptable — pertinent to a decision in this matter, we disagree with its result. Even if we review the agency’s interpretation of HMTA’s preemption provisions deferentially under Chevron, we still cannot conclude that its interpretation is a permissible reading of the statute in light of the strong presumption against federal preemption in matters traditionally regulated by the state. Neither the Supreme Court nor this one has ever definitively decided whether an agency’s determination that an explicit preemption provision in a statute it administers blocks some state action is reviewed according to Chevron. See, e.g., Illinois Commerce Comm’n v. ICC, 879 F.2d 917, 921 (D.C.Cir.1989) (<HOLDING>); City of New York v. FCC, 814 F.2d 720, 725-26
holding that chevron deference is due only to a reasonable interpretation made by the administrator of an agency recognizing that the question of whether courts should extend chevron deference to an agencys interpretation of an explicit preemption provision remains open holding regulations entitled to chevron deference holding that an agencys interpretation of its own regulations is entitled to deference recognizing the open question