U.S. airlines are pushing back against the possibility of COVID-19 testing before domestic flights after the Biden administration said it is "actively looking" at making it a requirement.

"It would have us testing Americans on airplanes that we all know are safe to be on," American Airlines CEO Doug Parker said during the carrier's Q4 earnings call.

Executives from Southwest and JetBlue echoed that sentiment, explaining that a domestic testing requirement would be too costly and pose logistical challenges. Centers for Disease Control and Prevention officials said Wednesday that the conversation is "ongoing" and that the agency is "actively looking at it."

The domestic testing would expand upon the administration's mandatory requirement for U.S.-bound travelers, which went into effect Tuesday. All travelers flying into the U.S. must now provide proof of a negative COVID-19 test, taken no more than three days before their flight, or they will be denied boarding.