Why is increased defense spending necessary according to European leaders?

European leaders stress that increased defense spending is urgently needed because Russia poses a threat not just to Ukraine but to all European nations. The defense policy expert emphasizes that 'the most important thing' is for all countries to 'step up' their defense budgets in response to this shared security challenge. The collective responsibility to enhance defense readiness is highlighted as essential, with the expert stating that Europe must 'scale up and speed up' its military preparedness. This unified approach reflects growing concerns about Russian aggression and underscores the strategic imperative of strengthening European security cooperation.