In order to comply with EPA (Environmental Protection Agency) regulations, and at a cost of about $5.2 million per ICBM, the rocket motors on 500 Minuteman III missiles will be replaced with new ones. These rockets will emit less toxic chemicals when used.
Thus, if the Minuteman III ICBMs have to be used in some future nuclear war, their rocket motors will not pollute the atmosphere.
(Strategy Page)

See? They _do_ care for the environment