The WTO said on Monday it had upheld the bulk of a ruling that Boeing received billions of dollars of subsidies to compete with Airbus, as both sides once again claimed victory in a long-running trade row.
The unfair subsidies included at least USD$2.6 billion in assistance from space agency NASA, which the World Trade Organization's appellate body agreed had allowed the US company to launch its 787 Dreamliner and caused "serious prejudice" to Airbus.
The ruling is the latest step in a seven-year dispute involving mutual claims of aid for the world's dominant plane makers and could, theoretically, lead to retaliation on both sides once the Geneva trade body's procedures are exhausted.
The WTO has already ruled that Airbus received illegal aid through a system of European government loans but the two sides cannot agree on the scope or impact of that ruling.
Most observers expect the United States and the European Union will eventually negotiate a settlement to end the row, since it could rumble on for years more amid pressure for compliance from both sides.
"We are ready to discuss at any moment, provided we are discussing on the basis of good questions," EU Trade Commissioner Karel de Gucht told a news conference in Geneva.
The EU has passed a deadline for compliance in the case against Airbus last December and the United States has begun a "compliance procedure", threatening to hit the European Union with sanctions worth USD$7 billion - USD$10 billion annually.
The United States will have six months to comply with the latest ruling once the WTO has formally adopted it, which it is expected to do at a meeting on March 23.
The biggest trade dogfight at the WTO has already lasted longer than the Uruguay Round negotiations that led to the birth in 1995 of the world trade body.
As so often in a saga with implications for jobs on both sides of the Atlantic, both sides gave their own interpretations as soon as the 598-page report came out.
The United States acknowledged that Boeing had been found to receive between USD$3 billion and USD$4 billion in subsidies in the form of federal research grants and local tax breaks, which is more than the USD$2.7 billion it conceded originally.
But US Trade Representative Ron Kirk called the decision "a tremendous victory" for the United States because according to Washington's calculations the WTO had previously found that European governments gave USD$18 billion in aid to Airbus.
"It is now clear that European subsidies to Airbus are far larger - by multiples - and far more distortive than anything that the United States does for Boeing," Kirk said.
Tim Reif, general counsel for Kirk's office, said the WTO had found Boeing lost 342 aircraft sales because of unfair subsidies to Airbus, while Airbus lost 118 sales because of unfair subsidies to Boeing.
"Any way of slicing it, it's pretty clear," he said.
De Gucht said the two cases were fundamentally different: "When you're discussing about Airbus you're discussing about repayable launch investments where the distorting element are the interest rates, whereas in the United States' case, the Boeing case, it's about grants, it's about cash gifts.
"The costs to EU industry from these long-term subsidies run into billions of euros. The US should now put an end to such harmful subsidies," he said in a statement.
The WTO had originally found that Boeing received at least USD$5.3 billion in subsidies including USD$2.2 billion in tax breaks through a defunct system of offshore corporations.
In Monday's appeal verdict, WTO judges accepted that the USD$2.2 billion of Foreign Sales Corporation tax breaks were no longer relevant but strengthened a finding that Boeing got almost USD$500 million in subsidies through bonds issued in Wichita, Kansas.
Boeing officials said that what the company had lost, by seeing the amount of illegal subsidies revised upwards, had been offset by reductions in the amount of harm caused to Airbus, which they said had been reduced sharply in the appeal.
The amount of harm will be important later when regulators try to assess how much, if any, retaliation is justified.
EADS subsidiary Airbus insisted the amount of damage identified by the WTO remained as high as ever and said it had lost USD$45 billion in sales due to Boeing subsidies.