Integrated Missile Defense Act of 2018 This bill addresses U.S. missile defense capabilities in response to nuclear threats from North Korea under the regime of Kim Jong-un. It urges or directs the Missile Defense Agency to accelerate the fielding of 20 additional ground-based interceptors with Redesigned Kill Vehicles (RKVs) at Missile Field 4 at Fort Greely, Alaska, and mate the RKVs with the newest booster technology; ensure the development and deployment of persistent space-based sensor architecture; plan a fully interoperable and integrated air and missile defense architecture; accelerate its hypersonic missile defense program and deploy such program in conjunction with a persistent space-based missile defense sensor program; seek to establish missile defense capabilities with allies and trusted partners of the United States; and pursue an increasingly rigorous testing regime and prioritize discrimination capabilities to improve missile defense effectiveness against current and future threats from countries hostile to the United States. .