The traditional dichotomy of security threats and responses cannot serve as a basis for developing national and international security arrangements and institutions in the Twenty First century. This article presents the concept of societal security and the notion of intermestic domain allowing to bridge state security and human safety challenges and to build trans-boundary linkages across domestic and international levels of response. Such holistic approach, that places societal security at the core, is manifested in the Solidarity Clause of the Constitution of the European Union. The implementation of the concept would provide for efficient development of security arrangements within the European Union, between European countries and the United States. Enhanced societal security across the Atlantic could become a core mission for the future work of NATO and the wider Partnership for Peace community.