Why would European countries keep big armies and navies for war?

European countries maintain large armies and navies to ensure national security and deter potential threats from rival states. The presence of formidable military forces serves as a deterrent against aggression and allows for rapid response to conflicts. Additionally, these forces enable countries to project power globally, protect trade routes, and uphold international alliances. Historical rivalries and geopolitical tensions in the region further drive the need for substantial military capabilities.