Measures to combat proliferation by analysing and preventing related financial transactions are referred to as counter-proliferation financing.
In contrast to nonproliferation, which focuses on diplomatic, legal, and administrative measures to dissuade and impede the acquisition of such weapons, counterproliferation focuses on intelligence, law enforcement, and sometimes military action to prevent their acquisition.
Technical means of verification, including space-based sensors that can scan large parts of the world, can provide early warning of long-range missile development.
Space-based Staring Infrared Sensors can detect the heat of rocket launching motors.
Various radars can monitor range and other characteristics, but they need to be in a place where they have line-of-sight to the missile trajectory.