With the ‘return of geopolitics’ in Europe signalled in earnest by Russia's illegal annexation of Crimea in 2014, this article examines the implications of Donald Trump's unpredictable US security policy for regional security in Northern Europe. While Trump's public rhetoric chastising NATO creates uncertainties for Europe's security, his administration's policy has remained committed to NATO's deterrence efforts. Against initial expectations for US-Russia rapprochement based on realpolitik during the Trump era, controversies and the administration's security policy actions have brought some unexpected discord in relations with Russia. A realist ‘grand bargain’ between Moscow and Washington that marginalises Nordic and Baltic security interests has become a remote prospect. Despite these reprieves, enhanced Nordic-Baltic security and defence cooperation is increasingly necessary. Overcoming occasional divergence in strategic preferences for effective military cooperation will ensure that the Nordic and Baltic states can strengthen regional deterrence and improve political relations with the Trump administration in an era of possible ‘transatlantic drift’.