Interesting twist, but not unexpected.
A group of US Airlines is teaming up against American, Delta, and United

By Benjamin Zhang 3 hours ago
According to the coalition, both Atlas and FedEX operate support flights for US military operations in the Middle East.
While the large legacy carriers use their own interational flights to feed domestic routes, smaller airlines such as JetBlue and Hawaiian credit the growing presence of international airlines such as the Middle Eastern three with increasing traffic for their domestic services.
In fact, JetBlue believes the Big 3's goal is to roll back the clock on the airline business.
"JetBlue is not unfamiliar with efforts from the legacy carriers to stifle competition" JetBlue general counsel James Hnat said on a conference call with the media.
"Legacy carriers are trying to protect themselves ... Open Skies is good for trade, economic growth and politics."
(AP) Furthermore, USAOS claimed that increased competition in the airline industry through Open Skies agreements will "generate approximately $4 billion in annual savings for passengers on U.S.-international routes."
USAOS also dimissed United, American, and Delta's claims that 800 airline jobs will be lost for every route they lose to a Middle Eastern airline.
"The threat of job loss is just a distraction from the whole picture," Hnat said during the call. "There are other jobs to be created. It’s a just political distraction."
The Big 3 haven't taken today's announcement without comment. In a swift response, the Partnership for Fair and Open Skies — the lobbying group representing United, Delta, and American — didn't mince words about the formation of the USAOS.
"This is a meaningless coalition without a cause," Partnership for Fair and Open Skies spokesperson Jill Zuckman said in a statement to Business Insider. "The only risk to our Open Skies agreements is the Gulf carriers themselves and their massive, market-distorting government subsidies. Of the 117 Open Skies agreements with the United States, 115 are working beautifully."
Obviously, this is a dispute that's not going away anytime soon, and today's entry of a third party has added an extra wrinkle to the story. Stay tuned for more action.