Civil Defense Preparedness Act of 2018 This bill amends the Homeland Security Act of 2002 to authorize the use of grants under the Urban Area Security Initiative (UASI) and the State Homeland Security Grant Program (SHSGP) to assist high-risk urban areas and high-risk states, respectively, to increase preparedness against rocket-propelled or other forms of kinetically-delivered weapons of mass destruction (WMD), including nuclear, biological, and chemical attacks. The bill includes a rocket-propelled or other form of kinetically-delivered WMD among the types of threats to critical infrastructure sectors and to U.S. populations that the Federal Emergency Management Agency (FEMA) must assess. FEMA must permit a grant recipient under the UASI and the SHSGP to use grant funds for joint projects with governmental entities for the procurement of WMD protective equipment and nuclear weapons attack building reinforcement.