First developed by Germany during World War II, cruise missiles eventually morphed into a weapon staple in the cold war between the United States and the former Soviet Union.
Today, though, they're increasingly seen as key components of defense arsenals in many countries around the world - some friendly to the US, some not.
Despite the White House focus on ballistic missile defense, the US must remain vigilant to both the proliferation and possibility of an unfriendly nation using an anti-ship, or land-based cruise missile - or an unmanned aerial vehicle (UAV), for that matter - to strike at the homeland or US targets elsewhere.
Those were key points made at a hearing on cruise missiles last month on Capitol Hill, sponsored by the respected Center for Strategic and Budgetary Assessments. In fact, about 70 countries now possess some type of cruise missile, according to Maj Gen. William Hodgkins, director of plans for the North American Aerospace Defense Command (NORAD).
Cruise missiles are smaller, cheaper, easier to hide, more mobile, and more difficult to track and shoot down than ballistic missiles - thus "increasingly attractive to US adversaries," says Thomas Mahnken of the Johns Hopkins School of Advanced International Studies. (One could easily fit, for instance, in a standard size shipping container.)
Add to that growing concern the fact that just last November, the radical Islamic group Hizbullah successfully flew an unmanned aerial vehicle over northern Israel for a couple of hours. Mr. Mahnken argued that a UAV armed with a dangerous weapon flying into US airspace and striking a "soft" target is "not out of the realm of possibility by any stretch of the imagination."
Experts at the hearing also noted that enough evidence exists of Al Qaeda's interest in even ultralight aircraft to justify concern over gaps in the Defense Department's low-level radar coverage of North America.
Such a vehicle, or even a low-tech, low-speed cruise missile, flying in at a low altitude remains hard for current air defense radar to spot.
At present, NORAD is working to fill in those radar gaps. It can't do this too quickly.
The Pentagon is conducting its 2005 comprehensive review of military strategy, its first since 9/11. As it proceeds, it needs to consider that better detection, and thus better thwarting of such objects, should help decrease US vulnerability to hostile attack.