Rep. Loretta Sanchez’s Nov. 30 column on the importance of missile defense to our national security missed the mark. While the California Democrat is correct that during tough fiscal times we can’t afford everything, she criticized spending on the only missile defense system we currently have in place to defend the homeland from missile attack, the Ground-Based Midcourse Defense system. Even in the direst of fiscal straits, the United States must adequately defend the homeland.

At less than one-thirtieth of 1 percent of federal spending, homeland missile defense is cheap insurance against a devastating ballistic missile attack on a U.S. city — even an accidental one. This insurance is more important than ever because ballistic missiles have become the weapon of choice for hostile countries.

The National Intelligence Estimate assesses  that Iran could achieve the ability to hit a U.S. city with a ballistic missile by 2015. U.S. Intelligence says that a recent explosion of unknown cause at a military installation 30 miles west of Tehran may have set back the Iranian ballistic missile program. The United States must take advantage of this by building up robust defenses before Iran can achieve an ICBM capability.

Other threats may be just over the horizon. During the past three years, Georgetown University students have conducted a striking and important study of China’s massive underground tunnel system, which could mean China has far more nuclear weapons and delivery systems than commonly believed.

Thanks to the cancelation of the European GMD site and reductions in the number of interceptors planned for the sites in California and Alaska, the U.S. homeland remains vulnerable to certain types of missile attack, even from technologically limited countries such as Iran and North Korea. In addition, plans to develop a new SM-3 missile that could fill the gaps in our homeland defense system (which both the Bush and Obama administrations have acknowledged exist) was zeroed out in the Senate Defense appropriations bill.

Missile defense is becoming more, not less, critical to U.S. national security. Now is not the time to cut funding to the only system guarding American cities against rogue state missiles.

— Rebeccah Heinrichs, adjunct fellow at the Foundation for Defense of Democracies