An aviation industry war could be on the horizon.
Regulators in Asian hubs like Singapore and Hong Kong have threatened to retaliate against tougher European Union rules.
The EU is to force airlines to start using take-off and landing slots that were frozen during the global health crisis.
And authorities controlling slots at major Asian airports are ready to slap similar conditions on European carriers flying to Asia's cities.
Carriers showed unity during the crisis as they tried to stay afloat.
But industry leaders say the dispute has rekindled differences across a fragmented sector.
In July the EU announced plans to force airlines to use 50% of their rights or lose them to rivals from next month.
Europe's mainly short-haul market has been showing signs of recovery.
Asian carriers say the new rules will penalise them as their long-haul networks will take longer to recover.
In Asia, long quarantines remain the norm and airlines operated just 14% of their 2019 international capacity in July.
Cathay Pacific last month warned that the slower recovery in Hong Kong meant it risked losing prized overseas airport slots.
And harming the city's hub status.
The EU broke with a global industry recommendation and tightened rules for the winter schedule season.
That was after heavy lobbying by low-cost carriers like Ryanair.
The European Commission said in July the 50% use rate - down from 80% in normal times - was chosen to ensure good use of airport capacity and to benefit consumers.
It did not respond immediately to a request for comment.