Disagreements between the U.S. and the European Union over airplane subsidies are escalating into a trade dogfight.

On Tuesday, the European Union decided to reactivate its complaint at the World Trade Organization alleging that airplane maker

Boeing

(BA) - Get Report

receives improper aid, according to media reports.

Both sides put their WTO cases on hold in January and agreed to try to negotiate a settlement. But talks hit an impasse, and the U.S. announced Monday that it was reopening its complaint against Boeing rival

Airbus

, a joint venture of the

European Aeronautic Defence and Space Co.

and

BAE Systems

.

The U.S. contends the launch aid that Airbus receives from European governments gives it an unfair advantage over Chicago-based Boeing. The E.U. claims that Boeing receives special subsidies in the form of state tax breaks and defense research grants.

Shares of Boeing were up 35 cents to $63.37 Tuesday.