12| M AZARR & F IOTT While there is still political disagreement over how permanent‘permanent’ means, the prospect of a non- rotational NATO force posture has implications for military mobility. Not least, there will be a need to explore whether the EU can financially support the modernisation of military bases on its territory or whether it should invest in missile and air defences to protect military bases and infrastructure, as well as civilian populations. Interestingly, the EU’s 2022 strategy for filling defence investment gaps specifically refers(on page seven) to the need for enhanced EU air and missile defence. T hus, this capability area could in time become part of the military mobility project and an integral element of future EU- NATO cooperation. Conclusion This Policy Insights paper has surveyed US and European security perspectives in the wake of Russia’s invasion of Ukraine. The range of US and European actions to resuscitate energetic, effective and focused security planning has been impressive, ranging from an expanded US posture to leadership from both NATO and EU as institutio ns, to commitments by many European countries for improved defence spending. Much remains to be determined and the follow- through on recent promises is essential. The relationship between NATO and the EU will require constant tending if it is to avoid tensions and recriminations, let alone reach its potential in efficient coordination. Overall, however, assessed against realistic standards for multinational action rather than against some theoretical ideal, the US and European response has been impressive, and the publicly expressed views of all parties are encouraging… at the moment. It is likely that some European countries could fail to meet the full scope of their commitments in the areas of defenc e and security. It is possible that NATO-EU coordination could still stall. But by far the biggest wild card going forward is American domestic politics – whether the brewing hostility toward traditional US commitments returns to the fore, either in a presidential administration or a radically different Congress. The trajectory of Western security cooperation is impressive, especially since the outbreak of the war in Ukraine, but whether it remains lasting is yet to be seen.