Lockheed Martin announced a lower-cost Patriot interceptor on Monday as militaries seek cheaper ways to counter drones and missiles, while defence contractors face competition from start-ups making low-cost weapons that can be produced at scale. Lockheed said its new PAC-3 Adapted Capability Effector (ACE) missile would cost less than half as much as its PAC-3 MSE interceptors, which cost roughly US$4 million per missile, according to US Army budget documents. Initial production could start...