Defense spending isn't supposed to be a direct subsidy, but the DoD does sometimes blatantly choose one product instead of better competing products based on industrial concerns. E.g. that tanker buy where Airbus won the competition, but the DoD reversed it and leaked emails showed that it was done purely to benifit Boeing. Or that the US Army refused to allow the widespread introduction of a modern infantry rifle that isn't made by Colt, forcing the US Marines to designating their new rifle as a "light machine gun".

Every country does this, since having your own defense industry is a massive strategic boon and keeping those high-tech jobs are good for the economy. But it's definitely anti-competitive behavior and the respective defense companies do get a lot more taxpayer money for the capabilities the country gets than would be optimal.