The EU says the same is true of USA tariffs imposed against subsidies to the A380 plane which is being taken out of production.
Tuesday's decision follows a WTO ruling a year ago that prompted the United States to begin imposing tariffs on 7.5 billion dollars in European Union goods and services over state aid for Europe-based aircraft maker Airbus.
Both sides filed complaints at the WTO on October 6, 2004, though the parallel cases have followed different timetables.
On top of Tuesday's $4bn, European sources have said the EU could also use dormant tariffs on a further $4bn of USA products left over from an earlier case, giving it firepower similar to that which Washington is able to use.
"Airbus did not start this WTO dispute, and we do not wish to continue the harm to the customers and suppliers of the aviation industry and to all other sectors impacted", said Airbus CEO Guillaume Faury in a written statement on Tuesday.
"The arbitrator determined that the level of countermeasures "commensurate with the degree and nature of the adverse effects determined to exist" amounts to $3.99 million per annum", the WTO ruled.
The spirits industry on both sides of Atlantic urged restraint and an end to tariffs.
The 16-year old dispute around so-called illegal state aid given to both Boeing and Airbus has been an ugly and costly battle on both sides.
For its part, Boeing insisted the tax break repeal by Washington state should have removed any basis for Tuesday's ruling. The decision has fallen on the side of the European argument, with the WTO authorizing the EU to impose tariffs on United States goods exported to the bloc.
"The EU will immediately re-engage with the U.S.in a positive and constructive manner to decide on next steps".
The company argued that the European Union should not impose the additional tariffs given that the tax provisions given by Washington state have been already repealed.
In October 2019, 15 years into the case, the US finally slapped tariffs of 25% on a series of non-aerospace goods including European wine, whiskey and cheese and a 10% tariff on European-built Airbus jets.
Reuters reports that while the bloc could enact the sanctions from after a WTO meeting on 26 October, analysts do not expect it to slap on the tariffs until after the U.S. election.
The ruling is the latest in a dispute that has been ongoing since 2004 between Boeing and its European rival Airbus. "President Trump looks at protecting the domestic interests but after this, there will be no re-election for him, so he might bring trade negotiations to the table", Bhanumurthy says.