Preventing Preemptive War in North Korea Act of 2018 This bill prohibits funds from being used without express congressional authorization for kinetic military operations in North Korea absent an imminent threat to the United States. The prohibition shall not apply to the introduction of the Armed Forces to: (1) repel an attack on the United States, its territories or possessions, the Armed Forces, or U.S. allies; or (2) rescue or remove U.S. personnel.