WASHINGTON, July 31 (UPI) -- The threat is real; the technology exists, and it is available and incredibly cheap; at least a half-dozen rogue states and well-funded terrorist groups around the world could afford it; and the menace puts in danger the lives of more than 200 million Americans. Yet almost nothing has been done about it.

The threat is that of old, short-range Scud ballistic missiles being launched with nuclear or biological warheads from large container cargo ships from outside U.S. territorial waters, some of the nation's leading experts in ballistic missile defense warn.

The entire populations of the U.S. Eastern Seaboard and West Coast, some 70 percent of the American people totaling more than 210 million people, are at risk from such attacks, experts have warned.

Tens of thousands of container cargo ships are at sea every day going to and from the United States. More than 1 million cargo containers a day are unloaded at Long Beach, Calif., alone.

The technology to intercept one or a few Scud missiles not only exists, it is mature and reliable. Earlier marks of Patriot missiles successfully defended the main Israeli centers of population in and around Tel Aviv from massive Scud missile attacks launched by Iraqi dictator Saddam Hussein during the 1991 Gulf War. Today's land-based U.S. Army Patriot PAC-3s, built by Raytheon, as well as the U.S. Navy's Aegis-radar-guided warship-deployed Standard Missiles-3s, have chalked up long and impressive records of interception against vastly faster and more difficult to hit intermediate-range ballistic missiles since then.

Since al-Qaida hijacked four airliners and successfully flew three of them into the sides of the two World Trade Center towers in New York City and into the Pentagon, killing more than 2,800 Americans on Sept. 11, 2001, the Bush administration has given top priority to boosting U.S. ballistic missile defense and port security. It has invested many billions of dollars in being able to detect any nuclear or biological weapons or material that terrorists or rogue states may attempt to smuggle into the United States through its ports or across the land borders from Canada and Mexico.

At the same time, ballistic missile defense programs able to shoot down short- and intermediate-range missiles also have been energetically improved. U.S. allies such as Israel, Japan and Taiwan have proven eager customers to buy the technology and the BMD weapons systems to protect their own population centers.

However, both the U.S. government and the American mainstream media have lost track of the threat posed by mounting Scuds and their light, very mobile launching pads in container ships and firing them at sea, experts warn.

In fact, the U.S. Missile Defense Agency and its boss, Lt. Gen. Henry "Trey" Obering III, have been warning for years about the grave danger posed by offshore ballistic missile launches. But on Capitol Hill and in the U.S. media alike, their warnings have fallen on deaf ears.

The advantages of such a mode of attack are obvious, experts say. The weapons systems involved are extremely cheap. Land-based ballistic missiles can be almost instantly identified with their countries of origin after takeoff. But Scuds launched from container ships cannot.

Writing for BusinessNet in November 2005, analyst Otto Kreisher noted there were already 75,000 anti-ship cruise missiles in circulation around the world in at least 70 countries, and many of them could easily be programmed to attack land targets instead.