In the book cyberspace capabilities, threats, and attacks are described. The principles of the cyberspace operations' missions, characteristics, design, and planning are presented. The cybersecurity organizations and forces are reported. The bases of the decision-making process, operations execution, and targeting in cyberspace are formulated. The principles of cyberspace operations support, synchronization, and assessment are outlined. The role of cybersecurity in Homeland, critical infrastructure protection, and other operations is depicted. The cybersecurity strategy, guidance, and policy in the U.S., NATO, the European Community, and the Republic of Moldova are shown.The book is recommended for civil and military specialists from academic, scientific, and application levels, for license, master's, and PhD degree students.