Poland’s Mass-Army Turn Is Reshaping NATO’s Eastern Flank

Planning a massive expansion of its armed forces by 2039, Poland is deliberately building a national capacity for sustained high-intensity war. The country is treating large-scale conflict no longer as hypothetical but as a baseline assumption shaping force structure, training and investment.

This shift draws directly on lessons from Ukraine and signals a recalibration of NATO’s eastern defence, where national mobilisation and endurance are increasingly emphasised over alliance reassurance alone.

Poland’s approach combines three elements rarely pursued together in contemporary Europe: numerical expansion; universal or near-universal military training; and the rapid integration of advanced strike, drone and AI-enabled systems.

While public debate has often focused on the headline figure of 500,000 personnel, the deeper significance lies in the conceptual break with the post-Cold War European model of defence. Warsaw is reorganising its military on the premise that future wars may be long, attritional and fought at scale.

At the centre of this transformation is a rejection of the minimalist force structures that dominated European defence planning after 1990. For decades, most European states prioritised professionalisation, expeditionary capability and small but technologically advanced forces designed for crisis management rather than territorial defence.