WASHINGTON — Six months ago, the Bush administration quietly eased some restrictions on the export of sensitive technologies to China. The new approach was intended to help American companies increase sales of high-tech equipment to China despite tight curbs on sharing technology that might have military applications.

But today the administration is facing questions from weapons experts about whether some equipment — newly authorized for export to Chinese companies deemed trustworthy by Washington — could instead end up helping China modernize its military. Equally worrisome, the weapons experts say, is the possibility that China could share the technology with Iran or Syria.

The technologies include advanced aircraft engine parts, navigation systems, telecommunications equipment and sophisticated composite materials.