Appendix 3: Information Sharing and Analysis Centers (ISACs) are a direct result of Presidential Decision Directive 63. The directive requested the public and private sector create a partnership to share important information about physical and cyber threats, vulnerabilities, intrusions and anomalies within and between industry sectors, and the National Infrastructure Protection Center (NIPC) and events to help protect the critical infrastructure of the United States. There are ISACs for many of the 17 critical infrastructures/key resources (CI/KR) sectors. Some but not all sectors have an ISAC while some sectors have multiple ISACs.