From the Heritage site

The proliferation of nuclear weapons and ballistic missiles to rogue states such as Iran and North Korea pose a grave danger to the lives of all Americans.

North Korea is currently developing a long-range ballistic missile that could soon carry a nuclear warhead all the way to Alaska or California. Iran already has missiles that can reach Europe, and could soon acquire nuclear weapons. These countries could share their missile and nuclear technologies with terrorists, who would in turn be able to directly threaten New York City and other American cities with short-range missiles.

Once terrorist-supporting states get their hands on a nuclear missile, they would be free to attack us and our allies with impunity, knowing full well we would think twice before sending our armed forces into a country that could retaliate with nuclear missiles. They would be emboldened to threaten their neighbors, assert dominance in their region, and further destabilize dangerous situations. Thus, they would gain sanctuary from which to export more terrorism.

Despite this present and growing danger, our government has moved too slowly to build the missile defense systems capable of defending us against such attacks. This is wrong. We have the technologies to do the job. And building a system is affordable, costing no more than 3 percent of the total annual defense budget.

We need to overcome the complacency of politicians, the spurious arguments of academics, and the narrow minded interests of government in order to defend Americans from this potential nuclear holocaust.