Modern espionage uses TECHINT (technical intelligence) along with
HUMINT (human intelligence). The latter depends on human penetration agents
and, with much luck and assuming no counter-penetration, is able to discern
the status and intentions of the enemy. TECHINT consists of SIGINT (signals
and communications interception) and PHOTINT (imaging intelligence). It is
more reliable than HUMINT but can also be expensive. Lyndon Johnson claimed
in 1967 that the entire space program could be justified ten times over
simply for its contribution to space photography: "Because tonight we know
how many missiles the enemy has and, it turned out, our guesses were way
off. We were building things we didn't need to build."
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