Shareholders may have cheered at the news, but American Airlines CEO Doug Parker sounds less than pleased with Qatar Airways’s interest in buying his company.

On Thursday, American Airlines aal revealed that state-owned airline Qatar Airways had voiced interest in buying a 10% stake of the company, worth about $808 million. The news pushed shares of American up 1.2% by the market’s close Thursday. But Parker wrote a rather icy letter to employees after the news broke, saying that he was puzzled by the bid.

“While anyone can purchase our shares in the open market, we aren’t particularly excited about Qatar’s outreach,” he wrote in a letter to employees seen by CNBC. “We find it extremely puzzling given our extremely public stance on the illegal subsidies that Qatar, Emirates, and Etihad have all received over the years from that government.”

American Airlines, alongside others such as United ual , have lobbed complaints at their Persian Gulf rivals, arguing that they receive an unfair advantage in the form of government subsidies.

“If anything,, this development strengthens our resolve to ensure the U.S. government enforces its trade agreements regarding fair competition with Gulf carriers,” Parker wrote in his letter.