"The June ruling was a very important victory for American aerospace workers and helped to level the competitive playing field for them," Nefeterius McPherson, a spokeswoman for the U.S. Trade Representative's office, said in a statement.
"However, the panel made two mistakes, and the United States is appealing these limited findings," she said.
The United States has hailed the WTO's June 30 ruling as a landmark victory in its long-running battle on Boeing's behalf against European government subsidies for aircraft manufacturer Airbus .
However, it did not win on every point and will now challenge the WTO panel's finding that European "launch aid" loans granted to Airbus over the course of 40 years were not part of an ongoing program of assistance.
It also is appealing the finding that certain launch aid contracts were not export subsidies, USTR said.
The EU announced on July 21 that it was appealing parts of the June 30 ruling that it lost.
Had it not, it would have been required to end prohibited export subsidies by Britain, Germany and Spain for Airbus' A380 airliner within 90 days, and withdraw other subsidies found illegal by the WTO or reverse their adverse effects.
U.S. trade officials emphasized they agreed with the overall reasoning of the June 30 ruling.
They said they would respond to the specific arguments raised in EU's appeal by the end of September.
Boeing lawyer Robert Novick has said he expects the WTO Appellate Body to issue its verdict on the case by the end of the year. But almost every stage of the complex litigation has already taken longer than expected.
A second WTO panel examining a EU complaint against U.S. government support for Boeing is expected to issue a preliminary confidential ruling in September. It would then be a number of months before the report is made public.
EU and Airbus officials say they are confident of a victory that would set the stage for a negotiated settlement. However, they are at disadvantage because the U.S. case against Airbus could be decided long before the EU case against Boeing.
That could expose the EU to U.S. retaliation if it loses the appeal and does not begin steps to comply. (Reuters)
