Boeing’s battle to crush Bombardier has encountered an unexpected obstacle.

Bloomberg reports that Airbus SE has agreed to acquire a majority stake in Bombardier Inc.’s C Series program, which the Commerce Department slapped with a 300% tariff it ruled in Boeing’s favor in a complaint alleging Bombardier had benefited from anti-competitive government subsidies.

Under the terms of the deal, Airbus won’t pay a dime up front for the C-Series, but will begin assembling the technologically advanced by poor-selling jetliner in the US in what Bloomberg said could be an effort to circumvent the tariffs.Airbus is adding another final assembly line for the C-Series at its factory in Mobile, Alabama, which will serve US customers and complement production in Canada, according to a company statement late Monday. However, Bloomberg says it’s unclear if the deal will allow the C-Series to avoid the tariffs.

It’s too soon to say if the new Alabama production line would enable the C Series to avoid U.S. tariffs. The duties were applied to C Series planes “regardless of whether they enter the United States fully or partially assembled,” according to a U.S. government fact sheet on the matter. Boeing said Airbus and Bombardier were just trying to get around the restrictions.

As part of the deal, Airbus will assume just over half of the interest in a partnership controlling the C-Series. Bloomberg says the European planemaker’s marketing muscle and production expertise boosts the viability of the all-new aircraft after more than $6 billion in development costs forced Bombardier to rely on government assistance.

The deal also thrusts Airbus into the middle of a trade spat between the two North American aerospace firms. In response to the Commerce Department’s ruling, Canadian Prime Minister Justin Trudeau canceled military equipment orders with Boeing, adding that they wouldn’t be reinstated until Boeing drops its complaint against Bombardier.