In what might become one of the biggest shakeups in aviation history, United Airlines CEO Scott Kirby has floated the idea of a merger with longtime rival American Airlines.

Kirby presented the concept to senior U.S. government officials, though it remains unclear whether any formal negotiations are underway or if the idea is still in its early exploratory stages.

If such a deal were to move forward, it would create an airline giant unlike anything currently in the U.S. market, or even the world for that matter. This giant airline would potentially surpass all competitors and consolidate even more power among the country’s already dominant four major carriers.

The proposal is ironically notable given Kirby’s history, he previously served as president of American Airlines before taking the job at United, giving him deep ties to both companies. Markets reacted immediately to the news, with American Airlines’ stock jumping more than 5% after-hours following the report, signaling investors are optimistic about such a deal.

However, before the excitement begins, any such merger would face huge regulatory scrutiny. U.S. officials have been cautious about airline consolidation due to concerns over competition, pricing, and consumer choice. Even if we were in a more business friendly environment, a deal of this magnitude would likely trigger a major antitrust legal battle.

The timing is also noticeable. The airline industry is facing rising fuel costs and uncertainty, which might be pushing some executives to explore strategies to remain competitive in an increasingly challenging market.