Gulf Coast LNG projects, including some already under construction, are facing a rash of new regulatory challenges and political pressure as environmental groups double down on calls for more climate considerations in permitting.

In the latest victory for opponents to liquefied natural gas exports, the U.S. Court of Appeals for the Fifth Circuit vacated Tuesday a state air permit granted to Sempra Infrastructure’s Port Arthur LNG.

In the opinion written by Judge James Graves, the court agreed with the argument by environmental group Port Arthur Community Action Network (PACAN) that the Texas Commission on Environmental Quality (TCEQ) had given Port Arthur greater emission limits than other LNG facilities approved in Texas without proper explanation.

“It therefore acted...