The paper begins by highlighting the difficulty of applying legal frameworks to hybrid threats due to the lack of a universally accepted definition. Terms like 'hybrid,' 'grey,' 'asymmetric,' and 'unconventional' are often used interchangeably, leading to ambiguity. The international environment is increasingly characterized by hybrid activities, which counter the goals of international law in promoting security, justice, and cooperation. The existing legal tools and institutions were largely developed during the Cold War and may not be fully equipped to address the complexities of covert operations in the grey zone – activities that harm another state without constituting acts of war. The shift from a relatively stable international order to a more volatile post-Cold War era further exacerbates this issue. Hybrid threats, operating below the threshold of warfare, exist within a realm of legal uncertainty. While education, prevention, and social awareness are important tools, the paper argues that a legal framework is necessary to navigate the legal ambiguities inherent in these threats and identify whether specific actions fall within legal boundaries. The law plays a crucial role in determining illegal conduct and identifying responsible actors; thus the core question becomes whether existing legal frameworks are sufficient or if new ones are needed to combat hybrid tactics.

The paper reviews existing definitions and characterizations of hybrid threats offered by NATO and the EU. While both organizations acknowledge the difficulty of defining hybrid threats due to their ever-evolving nature, they offer descriptions focusing on the combination of conventional and unconventional means, multidimensionality, and difficulty in detection and attribution. The paper highlights the challenges in achieving a consensus definition, proposing instead an analysis of state vulnerabilities and how to mitigate them. The review also encompasses a list of characteristics associated with hybrid threats including asymmetry, polymorphism, inequality, unaccountability, and adaptability, among others. These characteristics showcase the blend of unlawful acts and unethical behaviors within hybrid threats. The paper draws on various sources, including reports from the Centre of Excellence for Countering Hybrid Threats and the European Commission, to highlight vulnerabilities in infrastructure, cyberspace, and public administrations.

The paper employs a qualitative research methodology, primarily analyzing existing literature and legal frameworks. The author draws upon a wide range of sources, including reports from international organizations (NATO, EU, UN), academic publications, legal texts (European Convention on Human Rights, Geneva Conventions, UN Charter), and news articles. The analysis focuses on identifying the challenges in defining and countering hybrid threats, examining the legal frameworks applicable at international and European levels, and evaluating the limitations and capabilities of these frameworks in response to specific threats. The paper uses comparative analysis to contrast the experiences of democratic and authoritarian states in dealing with hybrid threats. It also uses case studies, including the annexation of Crimea and the events at the Moroccan-Spanish and Belarusian-Lithuanian borders, to illustrate how these tactics are applied. The legal analysis encompasses examination of international human rights law, the laws of war, principles of state responsibility, and the application of specific articles within relevant international treaties and conventions. The paper's approach is primarily descriptive and analytical, aiming to provide a comprehensive overview of the legal and conceptual aspects of hybrid threats.

The paper finds that the lack of a precise definition of hybrid threats poses a significant obstacle to effective countermeasures. Democratic states are particularly vulnerable due to their commitment to the rule of law and human rights, which can be exploited by actors employing hybrid tactics. Authoritarian states, conversely, often have less constraint in their actions. The analysis reveals that existing international law, particularly the UN Charter and the Geneva Conventions, may not be fully adequate to address the complexities and ambiguity of hybrid threats. The limitations of the UN Charter's restrictions on the use of force, the difficulties in attributing responsibility for actions in the grey zone, and the limitations of existing mechanisms for mutual assistance within the EU and NATO are explored. The paper highlights the concept of 'lawfare' – the manipulative use of law to advance political agendas – as a key component of hybrid warfare. The study further demonstrates that the European Convention on Human Rights (ECHR), while offering protection for human rights, also presents limitations when states seek to respond proportionately to hybrid threats. The paper concludes that while international and national law provide a framework for countering hybrid threats, there are challenges concerning attribution of responsibility, particularly when non-state actors are involved. The Articles on Responsibility of States for Internationally Wrongful Acts of 2001 and the Articles on the Responsibility of International Organisations of 2011, are referenced, highlighting their limitations in addressing the responsibility of non-state actors.

The paper's findings highlight the need for a more nuanced understanding of hybrid threats and their legal implications. The absence of a universally accepted definition hinders effective countermeasures and fuels the ambiguity that allows such threats to flourish. The vulnerability of democratic states to these tactics necessitates a proactive approach that balances the upholding of human rights with the need to defend national security. The discussion emphasizes the importance of international cooperation and the need for international organizations like NATO and the EU to adapt their structures and procedures to address hybrid threats more effectively. The limitations of existing legal frameworks, especially in attributing responsibility for actions carried out by non-state actors or proxies, need to be addressed. The paper suggests that states should strengthen national legislation to address vulnerabilities exploited by hybrid threats, such as in cyberspace, migration, and financial systems. The use of lawfare as a hybrid tactic underscores the need for a careful and well-informed approach to legal responses.

The paper concludes that while current international and national legal frameworks offer essential tools to counter hybrid threats, improvements are needed. Focusing on strengthening national legislation to address specific vulnerabilities and improving international cooperation are vital. The paper advocates for a proactive and flexible approach that balances the respect for human rights with the need for robust responses to protect national security. Future research could investigate the development of specific legal mechanisms and protocols for addressing the unique challenges posed by hybrid threats within the framework of existing international law. Further exploration into the effectiveness of various countermeasures and the role of international cooperation in preventing and mitigating these threats is also recommended.

The paper primarily relies on a review of existing literature and legal frameworks, limiting its scope for empirical analysis. The focus on the European context may limit the generalizability of some findings to other geopolitical regions. The study acknowledges the dynamic nature of hybrid threats, which inherently makes it challenging to provide definitive solutions or predictions. Further research employing mixed-methods approaches would enhance the understanding of hybrid threats and inform the development of more effective countermeasures.