"I continue to think that the only way out of the ridiculous series of disputes initiated by the U.S. is to agree on a set of globally applicable rules for the support of the civil aircraft industry, which would benefit both sides of the Atlantic," Airbus Group Chief Executive Tom Enders said in an emailed statement.
"The duopoly is no longer the framework of reference in the future," he said, noting recent support by the Quebec government for Canada's Bombardier.
In a separate statement, the EU's executive Commission called on the United States to withdraw a prohibited tax break for the new 777X jetliner following the WTO ruling.
"The panel has found that the additional massive subsidies of $5.7 billion provided by Washington state to Boeing are strictly illegal," EU Trade Commissioner Cecilia Malmstrom said.
"We expect the U.S. to respect the rules, uphold fair competition and withdraw these subsidies without any delay."
The United States has accused the European Union of failing to comply with earlier WTO rulings in a parallel case involving European government loans for Airbus.
(Tim Hepher and Foo Yun Chee - Reuters)