CHICAGO ( TheStreet) -- It may seem that United ( UAUA) is sitting pretty at Tokyo Narita, the most important airport in Asia with the fastest aviation growth, but that is not exactly the case. For all of its advantages at Narita, including the invaluable right to fly beyond Tokyo into Asia, and an unchallenged partnership with Japanese carrier ANA, United fears that continuing questions about the future of JAL, the other Japanese carrier, could slow its quest for an even better operating arrangement in Tokyo. United and ANA intend to file next month for antitrust immunity, which would enable the two carriers to discuss fares and schedules on their trans-Pacific routes. The arrangement would require approval by regulators in both countries. "We have worked to convince both of our governments that this is the way to move forward, and we want to make sure we don't get stuck in a delay," said Mark Schwab, United senior vice president for Alliances and International Affairs. He said the Japanese government could take several more months to determine what course to follow. United's two U.S. peers, American ( AMR) and Delta ( DAL), want to partner with JAL. The battle has escalated to the point that they are both offering to oversee investment of more than $1 billion into the bloated, potentially bankrupt carrier. Schwab won't say which U.S. partner for JAL he favors. But it seems clear that United would benefit from a continuation of the present arrangement in which American has a partnership with JAL. That partnership means that each of the world's three global aviation alliances has about a third of the traffic between the U.S. mainland and Japan, seemingly the distribution most likely to secure regulatory approval for antitrust immunity. Delta has maintained that if it were to partner with JAL, the two carriers would have 44% of mainland U.S.-Japan traffic. But if the Delta deal materializes, it is likely American and the Oneworld alliance would end up with a very limited share of the Japan market.