Defence industry regulation falls in between the ‘Low Politics' of ensuring market efficiency and the ‘High Politics' of preserving the national defence industrial and technological base. It has been exempt from internal market regulation and integrative initiatives have been managed on an intergovernmental base. In the past 10 years, however, the defence industries of the major EU powers have instigated a move from cross national collaboration to cross national consolidation. Cross border mergers and acquisitions has been carried out and pressures for regulatory mainstreaming is mounting. This raises the question: are we witnessing an incursion of spillover mechanisms into the ‘High Politics' domain of the defence industry? What are the drivers eroding the ‘High Politics' character of defence industry integration? Are market forces at play? Does it reflect pressures for institutional adaptation? Or may we attribute it to changing outlooks on the part of states so long exposed to the process of integration?