The United States has spent billions of dollars in the last decade on a missile defense system designed to protect the country from threats from other nations such as Iran and North Korea. Unfortunately, that system has proved to be as unreliable as it is expensive.

But that isn’t stopping Congress from unnecessarily expanding the program, now based in California and Alaska, to the East Coast, with rural western Maine as one of four sites under consideration.

FRUSTRATING RESULTS

Officials from the Missile Defense Agency, part of the Defense Department, were in Rangeley and Farmington last week to hear public comment on placing what is known as a Ground-based Midcourse Defense system at a Navy survival training camp in Redington Township, just east of Rangeley. They are doing the same at proposed locations in New York, Michigan and Ohio.

If the expansion is ultimately approved, one of those sites will become home to dozens of silos holding interceptors designed to shoot down intercontinental ballistic missiles fired by an enemy nation, with Iran the biggest presumed threat.

The facility, estimated to cost $3.4 billion, would be similar to those in Fort Greely, Alaska, and Vandenberg Air Force Base, California.

Those two sites were developed hastily following a 2002 order by then-President George W. Bush to increase air defense capabilities. There are now four interceptor missiles at Vandenberg and 26 at Fort Greely, with 14 more to be placed in Alaska by 2017, at an additional cost of $1 billion.

The Pentagon has spent an estimated $40 billion thus far on the ground-based missile system, with frustrating results.

In 17 tests, the system has registered just nine hits. What’s more, those tests have been conducted in controlled conditions favorable to the system operators and against targets with neither the range nor the speed of intercontinental ballistic missiles.

NEEDLESS EXPANSION

Placing missiles closer to the presumed enemy launch site, as well as to likely targets on the East Coast, will not help, either.

That’s the conclusion of the Pentagon’s 2010 Ballistic Missile Defense Review, which said that the missile sites in Alaska and California were sufficient to protect the U.S. from an attack within the capabilities of Iran or North Korea “for the foreseeable future.”

The review, approved by then-Defense Secretary Robert Gates, also recommended against developing the missile program “at the same accelerated rate or with the same level of risk as in recent years.”

Instead, it advocated for improving the missile system’s ability to sense targets from the Middle East and to discern decoys and debris from actual missiles.

Vice Adm. James D. Syring, director of the Missile Defense Agency, came to a similar conclusion last year, writing to Sen. Carl Levin, chairman of the Senate Armed Services Committee: “There is no validated military requirement to deploy an East Coast missile defense site.”

MISGUIDED CONGRESS

That leaves only non-military reasons, such as the infusion of federal dollars and the promise of new jobs, for creating an additional site. And that likely explains why Congress, not the Pentagon or the Obama administration, is pushing the matter.

(In Maine, Republican U.S. Sen. Susan Collins has advocated for a missile site in Maine to be considered, while U.S. Sen. Angus King, an independent, said he is awaiting the results of an environmental impact study.)

The potential economic benefits of a new site, however, are disputed. And in any case, it is the proficiency of the system, not its effect on the local economy, that should be the deciding factor on matters of national defense.

Regardless, each of the proposed sites will now undergo the environmental review, funded by $30 million set aside in the defense budget by House Republicans. It is expected to take two years.

To be sure, there are environmental concerns at each of the sites, particularly in Maine, where the silos would dot the surrounding pristine and rugged mountains.

But we don’t need an environmental review to tell us that spending billions to expand an erratic missile defense system is a bad idea.