The World Trade Organization (WTO) issued a ruling on Monday in response to a dispute between the US and the EU over government subsidies Boeing allegedly received.
In the ruling, the WTO found that Seattle-based Boeing had received $5.3 billion in illegal subsidies over the last 25 years, a figure that was far less than subsidies received by its European rival Airbus.
The complaint was filed against Boeing by the EU in 2005.
In a similar ruling last May, the WTO ruled on a US complaint that Germany, France, the United Kingdom and Spain had provided Airbus with $18 billion in illegal subsidies.
The complaint was upheld but, according to Reuters, there is still years of negotiations as both sides work out how to comply with the ruling.
Both companies have been locked in a lengthy trade dispute in which both sides has threatened sanctions and filed complaints with the WTO that the other is receiving aid from their respective governments.
After the Boeing ruling, U.S. Trade Representative Ron Kirk said to the Associated Press that European subsidies were "far more distortive than anything that the United States does for Boeing."
Both sides on Monday claimed a victory with the ruling.
"This decision is a tremendous victory for American manufacturers and workers," Kirk said in a statement, according to CNN.
For European trade representatives, the ruling proved their complaints were justified.
"Today's ruling vindicates the EU's long-held claims that Boeing has received massive U.S. government hand-outs in the past and continues to do so today," said EU Trade Commissioner Karel De Gucht, as quoted by CNN.
According to Reuters, some of the illegal subsidies included $2.6 billion from NASA, which helped the company launch the newest addition to Boeing's fleet, the 787 Dreamliner.
The US has six months to comply with the ruling against Boeing once it has been adopted, which is expected to happen later this month.