KEN
SHIELD
Missiles designed to destroy incoming nuclear warheads
fail frequently in tests and could increase
global risk of mass destruction
By Laura Grego and David Wright
Laura Grego is a senior scientist in the Global Security
Program at the Union of Concerned Scientists and has
focused on ballistic missile defense.David Wright is co-director of the Global Security
Program and is an expert on technical aspects of
nuclear weapons policy.BRO
SECURITYIllustrations by Tavis Coburn62 Scientific American, June 2019EarliEr this yEar in a high-stakEs summit mEEting, thE lEadEr of north korEa, kim Jong-un, and
U.S. president Donald Trump failed to agree on a way to end North Korea’s missile and nuclear
weapons program. Within days of the summit, satellite imagery showed that Kim was rebuilding
some of North Korea’s rocket facilities.
In 2017 Kim’s government had tested its first long-range missiles and soon followed up with
a test of what appeared to be a powerful hydrogen bomb. After those operations, Trump told
Americans not to worry. “We build the greatest military equipment in the world,” he said on the
Fox News television channel. “We have missiles that can knock out a missile in the air 97 per-
cent of the time. If you send two of them, they are going to get knocked down.”