After Apple's patent complaints against HTC, The HTC One X and the HTC EVO 4G LTE shipments were affected by these proceedings, HTC has resolved the issue and the review process of the US customs is now done and the devices are free to enter the country.
HTC statement announced the End of the import ban:
"HTC devices have been released by US Customs as they are in compliance with the ITC's ruling. HTC has completed the review process with US Customs and HTC devices have been released, as they are in compliance with the ITC's ruling. Future shipments should continue to enter the US and we are confident that we will soon be able to meet the demand for our products."