The US Department of Transportation has finalised a ruling that permits American Airlines, Delta Air Lines, Hawaiian Airlines and United Airlines to begin operating an additional 12 daytime flights to Tokyo Haneda airport.
All 12 of the awarded slots are for daytime flights.
The DOT's decision allows American to serve Haneda from Dallas/Fort Worth and Los Angeles, and enables Delta to fly there from Atlanta, Detroit, Honolulu, Portland and Seattle.
It permits Hawaiian to serve Haneda from Honolulu and gives United rights to serve the airport from Chicago, Los Angeles, Newark and Washington-Dulles.
The order, which finalises a tentative award issued by the DOT in May, settles a battle among US airlines for the highly coveted rights to serve Haneda during daylight hours.
The carriers will begin the flights "as early as March 2020", the agency says.
The 12 newly awarded slots add to six existing Haneda slots awarded to US carriers by a 2016 amendment to the US-Japan air services agreements.
That agreement specifies that five of those slots be daytime flights and one be a nighttime flight.
The same four US carriers hold those six previously awarded slots.
American serves Haneda from Los Angeles, Delta from Los Angeles and Minneapolis-St Paul, Hawaiian from Honolulu and Kona, and United from San Francisco, according to Cirium schedules data.