A merger of two of the biggest US carriers could be the largest ever airline consolidation in more than a decade.

American shares were up about 4%, while United rose around 2%.

Both stocks have slid in recent weeks as the US-Israeli war with Iran sent jet fuel prices sharply higher, with American plunging 14.1% and United slumping 10.4% since the conflict began in late February.

Kirby raised the idea during a Feb 25 White House meeting focused on the future of Washington’s Dulles airport, sources told Reuters.

He argued a combined airline could better compete internationally, where foreign carriers control a majority of long-haul seat capacity to and from the US, despite most passengers being US citizens.

Industry officials and antitrust experts said approval would face steep hurdles, citing concerns over competition, higher fares, job losses and significant route overlap in an already highly concentrated US airline market dominated by four large carriers.

United and American declined to comment, and the White House did not respond to requests for comment.