This thesis focuses on the ethical aspects of soldiers of the Army of the Czech republic participating in the foreign operations, not only in relation to the legality and legitimacy of military intervention, but also from the point of view of practical ethical questions of soldiers sent to perform tasks in these operations. The first part of this thesis introduces the Army of the Czech Republic as a tool to ensure national security and national sovereignty, built with emphasis to fulfill military traditions, virtues and professional ethics. Later, in historical and contemporary contexts summarizes the basic ethical solutions for the legitimate use of force to resolve international conflicts. The second part reflects the umanitarian and security operations taking place in the former Yugoslavia, Iraq and Afghanistan as the consequences of massive human rights violations, ethnic violence and global terrorism. In the context of the ethical and Christian dimension of legitimate use of military means, summarizes the basic issues while solving security threats and enforcing national interests.