Artificial intelligence (AI) brings significant societal progress and it also revolutionizes the cybersecurity sector. Thus, studying the security problems induced by the deep fusion of AI and cyberspace security becomes significant. In this article, we systematically analyze the major national security issues induced by the fusion, involving political, economic, social, and national defense securities. These issues aggravate the existing security risks and trigger new threats. Moreover, new attack scenarios are analyzed, including autonomous and large-scale denial-of-service attacks, intelligent and disguised social engineering attacks, and intelligent and targeted malicious code attacks. Subsequently, future AI-enabled attack types such as situation-awareness covert attacks, distributed autonomous-collaboration attacks, and self-evolving attacks are explored. To effectively address the security threats of AI-enabled cyber attacks, we suggest that an intelligent network attack and defense system should be established and its capabilities upgraded to construct equivalent capabilities. Sharing of AI security data assets should be encouraged to develop a data-centered path for AI-enabled network attack and defense technologies. Furthermore, the AI-enabled network attack and defense technologies should be evaluated and verified through counterwork, enabling these technologies to be practically implemented.