Is a trial judge's decision to limit cross-examination permissible?

Montoya claims that the district court improperly limited cross-examination of Winchester, and that those limitations violated his Sixth Amendment rights. We review a trial judge's decision to limit cross-examination for abuse of discretion. United States v. Bonanno, 852 F.2d 434, 439 (9th Cir.1988), cert. denied, 488 U.S. 1016 (1989). Whether cross-examination restrictions are so severe as to be violative of the Sixth Amendment's confrontation clause is a legal question that we review de novo. United States v. Vargas, 933 F.2d 701, 704 (9th Cir.1991).