DALLAS — U.S. airlines have been sparring for several years with fast-growing Persian Gulf rivals that seem to be poaching passengers from the Americans. Now, a CEO’s comment that dragged 9/11 into the debate has escalated the fight.

The three largest U.S. airlines claim that three big Gulf carriers have received more than $40 billion in subsidies from their governments since 2004, making competition with them unfair because their costs are artificially low. The CEOs of American, United and Delta are asking federal officials to renegotiate or kill treaties that allow airlines from Qatar and the United Arab Emirates to increase flights to the U.S. After the terror attacks of Sept. 11, 2001, Congress approved $5 billion in cash aid and up to $10 billion in loan guarantees to help U.S. airlines survive a sharp drop in travel. The Gulf airlines contend that those payments amounted to subsidies.

In response to those claims, Delta CEO Richard Anderson seemed to link the Gulf carriers and their nations to the 9/11 attacks, in which American Airlines and United Airlines jets were crashed into the World Trade Center and the Pentagon.

“It’s a great irony to have the United Arab Emirates from the Arabian peninsula talk about that, given the fact that our industry was really shocked by the terrorism of 9/11, which came from terrorists from the Arabian peninsula,” Anderson said on CNN.