With the catastrophic invasion of Ukraine by Russia, war has returned to Europe some three decades after the end of the Cold War and seven decades after the end of World War II. The Cold War and post-Cold War international and European security architecture has been steadily eroding. The record of the 21st century shows military invasions and interventions as well as the collapse of the arms control and security architecture inter alia of the ABM Treaty in 2002, the CFE Treaty in 2007/2011, the Budapest Memorandum in 2014, the INF Treaty in 2019, and the Open Skies Treaty in 2021. The immediate priorities should be a cease fire and status quo ante prior to mid-February in Ukraine and measures to avoid: new and destabilizing military deployments; dangerous encounters between Russian and NATO/US forces; raising nuclear alert levels; and nuclear threats. Previously Russia and the US have exchanged nuclear arms control and security proposals; how could this security dialogue be resumed after end of hostilities to defuse US/NATO-Russia tensions; how to reestablish a common European security architecture of arms control measures to prevent an all-out arms race; how to prevent new riskier confrontations; and what could be the priorities for NATO’s new Strategic Concept due to be adopted at its Madrid Summit in June 2022. These and related forward looking developments concerning nuclear arms control were the focus of this expert discussion on 21st April 2022.