This paper deals with ensuring the sustainability of the financial system and combating hybrid threats in relation to anti-money laundering and counter-terrorist financing (AML/CTF) measures. International cooperation in the field of combating hybrid threats is only at the beginning, and in many ways, the experience of international cooperation in the fight against money laundering and terrorist financing, which is based on many years of experience in the institutional and legislative fields, could be used. Hybrid threats are constantly changing and evolving, which means our response to them must also constantly evolve and adapt. The aim of the presented study is the analysis of the problem of the legalization of income from criminal activity and the financing of terrorism and their possible relationship with the fight against hybrid threats and maintaining the stability of the financial system.