The launch of Sprint’s flagship EVO 4G LTE has been delayed indefinitely and supply of AT&T’s flagship HTC One X will be constrained as a result of ongoing patent disputes between HTC and Apple. HTC confirmed in a statement emailed to BGR on Tuesday evening that shipments of its new EVO 4G LTE and One X smartphones have been held up by United States Customs as part of an International Trade Commission investigation. Before the phones can clear Customs, the ITC will need to determine that HTC’s new handsets are in compliance with an earlier ruling.

“The US availability of the HTC One X and HTC EVO 4G LTE has been delayed due to a standard U.S. Customs review of shipments that is required after an ITC exclusion order,” an HTC spokesperson said. “We believe we are in compliance with the ruling and HTC is working closely with Customs to secure approval. The HTC One X and HTC EVO 4G LTE have been received enthusiastically by customers and we appreciate their patience as we work to get these products into their hands as soon as possible.”

Sprint was scheduled to launch the EVO 4G LTE, a customized version of the One X, on May 18th for $199.99 on contract. AT&T made the One X available earlier this month, however the device is now listed as out of stock on AT&T’s website and supply will be constrained until shipments clear Customs. The import delays mark the first time one of Apple’s numerous patent complaints against rivals in the U.S. has paid off.

Shares of HTC stock tumbled more than 6% on news of the import delays.