WASHINGTON — Leaders of the U.S. Missile Defense Agency were effusive about the new technology.

It was the most powerful radar of its kind in the world, they told Congress. So powerful it could detect a baseball over San Francisco from the other side of the country.

If North Korea launched a sneak attack, the Sea-Based X-Band Radar — SBX for short — would spot the incoming missiles, track them through space and guide U.S. rocket-interceptors to destroy them.

Crucially, the system would be able to distinguish between actual missiles and decoys.

SBX "represents a capability that is unmatched," the director of the Missile Defense Agency told a Senate subcommittee in 2007.

In reality, the giant floating radar has been a $2.2 billion flop, a Los Angeles Times investigation found.

Although it can powerfully magnify distant objects, its field of vision is so narrow that it would be of little use against what experts consider the likeliest attack: a stream of missiles interspersed with decoys.

SBX was supposed to be operational by 2005. Instead, it spends most of the year mothballed at Pearl Harbor in Hawaii.

The project not only wasted taxpayer money but left a hole in the nation’s defenses. The money spent on it could have gone toward land-based radars with a greater capability to track long-range missiles, according to experts who studied the issue.

Expensive missteps have become a trademark of the Missile Defense Agency, an arm of the Pentagon charged with protecting U.S. troops and ships and the American homeland.

Over the last decade, the agency has sunk nearly $10 billion into SBX and three other programs that had to be killed or sidelined after they proved unworkable, The Times found.

"You can spend an awful lot of money and end up with nothing," said Mike Corbett, a retired Air Force colonel who oversaw the agency’s contracting for weapons systems from 2006 to 2009. "MDA spent billions and billions on these programs that didn’t lead anywhere."

The four ill-fated programs were all intended to address a key vulnerability in U.S. defenses: If an enemy launched decoys along with real missiles, U.S. radars could be fooled, causing rocket-interceptors to be fired at the wrong objects — and increasing the risk that actual warheads would slip through.

In addition to SBX, the programs were:

The Airborne Laser, envisioned as a fleet of converted Boeing 747s that would fire laser beams to destroy enemy missiles soon after launch, before they could release decoys.

It turned out that the lasers could not be fired over sufficient distances, so the planes would have to fly within or near an enemy’s borders continuously. That would leave the 747s all but defenseless against anti-aircraft missiles. The program was canceled in 2012, after a decade of testing.

The cost: $5.3 billion.

The Kinetic Energy Interceptor, a rocket designed to be fired from land or sea to destroy enemy missiles during their early stage of flight. But the interceptor was too long to fit on Navy ships, and on land, it would have to be positioned so close to its target that it would be vulnerable to attack. The program was killed in 2009, after six years of development.

The cost: $1.7 billion.

The Multiple Kill Vehicle, a cluster of miniature interceptors that would destroy enemy missiles along with any decoys. In 2007 and 2008, the Missile Defense Agency trumpeted it as a "transformational program" and a cost-effective "force multiplier." After four years of development, the agency’s contractors had not conducted a single test flight, and the program was shelved.

The cost: nearly $700 million.

These expensive flops stem in part from a climate of anxiety after Sept. 11, 2001, heightened by warnings from defense hawks that North Korea and Iran were close to developing long-range missiles capable of reaching the United States.

President George W. Bush, in 2002, ordered an urgent effort to field a homeland missile defense system within two years. In their rush to make that deadline, Missile Defense Agency officials latched onto exotic, unproved concepts without doing a rigorous analysis of their cost and feasibility.

Members of Congress whose states and districts benefited from the spending tenaciously defended the programs, even after their deficiencies became evident.

These conclusions emerge from a review of thousands of pages of expert reports, congressional testimony and other government records, along with interviews with dozens of aerospace and military affairs specialists.

"The management of the organization is one of technologists in their hobby shop," said L. David Montague, a former president of missile systems for Lockheed Corp. and co-chairman of a National Academy of Sciences-sponsored review of the agency. "They don’t know the nitty-gritty of what it takes to make something work."

This leads, he said, to programs that "defy the limits of physics and economic logic."

Of the SBX radar, Montague said: "It should never have been built."

Retired Air Force Gen. Eugene E. Habiger, former head of the U.S. Strategic Command and a member of the National Academy panel, said the agency’s blunders reflected a failure to analyze alternatives or seek independent cost estimates.

"They are totally off in la-la land," Habiger said.

Senior officials who promoted the four programs defend their actions as having helped to create a new missile defense "architecture." Regarding SBX, they said it was much less expensive than a network of land-based radars and could be put in place more rapidly.

Henry A. Obering III, a retired director of the Missile Defense Agency, said any unfulfilled expectations for SBX and the other projects were the fault of the Obama administration and Congress — for not doubling down with more spending.

"If we can stop one missile from destroying one American city," said Obering, a former Air Force lieutenant general, "we have justified the entire program many times over from its initiation in terms of cost."

The agency’s current director, Vice Adm. James D. Syring, declined to be interviewed. In a written response to questions, the agency defended its investment in the four troubled programs and asserted that the nation’s missile defense system was reliable.

"We are very confident of our ability … and we will continue to conduct extensive research, development and testing of new technologies to ensure we keep pace with the threat," the statement said. It called SBX an "excellent investment."

Boeing Co., the agency’s prime contractor for homeland defense, designed SBX. Raytheon Co. built the system’s radar components. Both companies are among the world’s biggest defense contractors and major political donors.

A Boeing spokesman said that SBX has "sufficient capability to execute its role with speed, precision and accuracy."

Representatives of Raytheon declined to be interviewed.

——

The Missile Defense Agency came into being during the Reagan administration and has 8,800 employees and a budget of about $8 billion a year.

The agency oversees three missile defense systems. Aegis defends Navy ships. The Terminal High Altitude Area Defense system consists of Patriot rockets to safeguard troops in the field.

The third component is the Ground-Based Midcourse Defense system, or GMD, designed to protect the U.S. homeland from long-range missiles. All four of the troubled programs examined by The Times were intended to bolster GMD.

The country’s defense against a massive missile strike by Russia or China still depends on deterrence: the Cold War notion that neither nuclear power would attack the U.S. for fear of a devastating response.

GMD is intended to protect against a limited attack by a less-imposing adversary, such as North Korea or Iran, by destroying enemy warheads in flight, a supreme technical challenge.

Rocket-interceptors would climb into space from silos at Vandenberg Air Force Base in Santa Barbara County and Fort Greely, Alaska. At the tip of each interceptor is a heat-seeking "kill vehicle" designed to separate from its boost rocket in space, fly on its own and crash into an incoming warhead.

GMD’s roots go back to the Clinton administration. Its development was accelerated after Bush, in December 2002, ordered the Pentagon to field "an initial set of missile defense capabilities" to protect the U.S. homeland by 2004.

Then-Secretary of Defense Donald H. Rumsfeld exempted the Missile Defense Agency from standard procurement rules, freeing it to buy new technology without the customary vetting. Rocket-interceptors were deployed before the kill vehicle and other crucial components had been proved reliable through testing.

Despite its shortcomings, GMD became operational in 2004. In the nine flight tests conducted since then, the system has successfully intercepted a mock enemy missile only four times.

GMD’s ability to distinguish missiles from decoys, debris and other harmless objects — "discrimination," in missile defense jargon — has been a persistent concern.

Powerful, precise radar guidance is key to effective missile defense. Without it, the system cannot be depended on to distinguish real from illusory threats and track enemy missiles so the kill vehicles can find and destroy them.

In the event of an attack, radar would also have to provide immediate, accurate "hit assessments" — confirmation that an enemy missile had been destroyed. Defense experts say that without this information, GMD could rapidly deplete its limited inventory of interceptors: four at Vandenberg and 26 at Fort Greely.

Existing early-warning radars, based on land in Alaska, California, Britain and Greenland and on Navy ships, provide some of the needed capability. But their range is limited by Earth’s curvature, and neither they nor orbiting satellites are powerful enough to determine whether approaching objects are benign or threatening.

X-band radar is powerful enough. Its short wavelength — located in the X band of the radio wave spectrum — allows for more detailed imagery, and thus better discrimination.

Missile defense plans drawn during the Clinton administration envisioned as many as nine land-based X-band radars to complement the early-warning radars and provide complete coverage across the Atlantic and Pacific oceans.

In 2002, faced with Bush’s deadline for deploying GMD by 2004, Missile Defense Agency officials chose not to add multiple X-band radars on land and opted instead for a single, seaborne version.

It would be based at a specially prepared berth in Alaska’s Aleutian Islands, an ideal location for detecting a North Korean missile attack, and would be moved around as needed.

Thus was born SBX.

——

Boeing’s designs called for the huge radar to be seated atop a specially modified off-shore drilling platform.

The Missile Defense Agency acquired the platform from a Norwegian company in 2003 and had it towed across the Atlantic to a shipyard in Brownsville, Texas. There, it was fitted with a propulsion system, a helicopter landing pad and living quarters for a crew of about 100. Cranes lifted the radar and its pearl-white protective dome into place.

The semi-submersible structure was nearly 400 feet long and 26 stories high. It weighed 50,000 tons.

Obering and his predecessor as director of the missile agency told Congress that SBX would be operational by the end of 2005. That proved incorrect.

SBX met standards for commercial ships — but agency officials had failed to take into account the Coast Guard’s stricter standards for vessels destined for the kind of hazardous conditions found in the Aleutians.

To meet the requirements, the missile agency had to spend tens of millions of dollars to fortify SBX against the sustained 30-foot swells and fierce gales common at its intended home port in Adak, Alaska, known as the "birthplace of the winds."

That work, completed by Boeing in September 2007, included installing eight 75-ton anchors embedded in the ocean floor at Adak.

Missile Defense Agency officials spoke glowingly of SBX’s technical capabilities.

"It is the most powerful radar of its kind in the world and will provide the (GMD) system a highly advanced detection and discrimination capability," Obering told the Senate’s defense appropriations subcommittee on May 10, 2006.

Agency news releases touted SBX’s ability to perform critical "hit assessment functions," informing U.S. commanders instantly whether rocket-interceptors had taken out incoming missiles.

At a Senate hearing on April 11, 2007, Obering was asked about the GMD system’s ability to distinguish enemy missiles from decoys. He replied that SBX would help give the U.S. "a tremendous leg up" in this regard.

To emphasize his point, Obering testified repeatedly that SBX could see a 3-inch-wide object from across the continent.

"If we place it in Chesapeake Bay, we could actually discriminate and track a baseball-sized object over San Francisco," he told a Senate subcommittee on April 25, 2007.

Yet because of Earth’s curvature, SBX would not be able to see a baseball at such a distance — about 2,500 miles — unless the ball was 870 or more miles above San Francisco.

That is about 200 miles higher than the expected maximum altitude of a long-range missile headed for the U.S., technical experts told The Times.

"In the practical world of ICBM (inter-continental ballistic missile) threats, this baseball analogy is meaningless," said C. Wendell Mead, an aerospace engineer who served on the National Academy of Sciences panel.

Obering, in an interview, said his remarks to Congress were intended not to mislead but rather to provide "a good layman’s view of the range of the radar." He added, "The range of that radar is farther than anything else we had."

——

SBX’s powers of magnification belied a fundamental shortcoming. The radar’s field of vision is extremely narrow: 25 degrees, compared with 90 to 120 degrees for conventional radars.

Experts liken SBX to a soda straw and say that finding a sequence of approaching missiles with it would be impractical.

"It’s an extremely powerful soda straw, but that’s not what we needed," said Harvey L. Lynch, a physicist who served on the National Academy of Sciences panel.

In the event of an attack, land-based early warning radars could, in theory, identify a specific point in the sky for SBX to focus on. But aiming and re-aiming the giant radar’s beam is a cumbersome manual exercise. In combat conditions, SBX could not be relied on to adjust quickly enough to track a stream of separate missiles, radar specialists said.

SBX’s limitations make it "irrelevant to ballistic missile defense," said David K. Barton, a physicist and radar engineer who took part in the National Academy review and who has advised U.S. intelligence agencies.

"Wherever that beam can be pointed, it can cover whatever is within it," Barton said. "But obviously that isn’t going to cover the whole Pacific for a stream of attacking missiles that are separated by many minutes. … Even if there are only four missiles, (an adversary) could separate them."

Ronald T. Kadish, the Missile Defense Agency’s director from 1999 to mid-2004, defended the decision to develop SBX, saying it was "four or five times" less expensive than installing land-based X-band radars.

Another "important consideration," Kadish said in an interview, was that the seaborne radar could be made operational quickly, without requiring the building of an X-band installation in Alaska or negotiating with foreign governments for other sites on land.

Kadish, a retired Air Force lieutenant general, said SBX "seemed to provide the basis for detection and discrimination that we were lacking."

The National Academy review, however, found that the missile agency "unnecessarily compromised the performance" of GMD by failing to make greater use of X-band radars on land. The panel’s 2012 report said the homeland defense system’s "discrimination problem must be addressed far more seriously."

A panel of the Pentagon’s Defense Science Board, after a two-year review, reached a similar conclusion in 2011: "The importance of achieving reliable midcourse discrimination cannot be overemphasized."

To address this vulnerability, the U.S. had installed one land-based X-band radar in Japan in 2006, and a second was added in 2014. The two radars are well-positioned to detect launches from North Korea. Yet both would lose track of U.S.-bound missiles after about 930 miles because of Earth’s curvature.

Barton said that to give rocket-interceptors enough time to knock out enemy missiles, U.S. radar would have to track the incoming weapons continuously after launch, "from cradle to grave."

(END OPTIONAL TRIM)

——

One of SBX’s intended functions was to participate in tests of the GMD system. A mock enemy missile would be launched over the Pacific, and SBX would track the target and guide rocket-interceptors.

The radar’s performance in those exercises has fallen short.

During a 2007 test, "SBX exhibited some anomalous behavior," requiring "adjusted software," the Pentagon’s Operational Test and Evaluation Office said in a report.

The report said SBX had not served as the primary radar for any test in which an interceptor had managed to destroy a target.

In January 2010, SBX was the sole radar for a test in which an interceptor tried to knock out a target launched from the Marshall Islands. SBX "exhibited undesirable performances that contributed to the failure to intercept," the Pentagon evaluation office reported.

Outside experts who had access to flight-test data from the 2010 test told The Times that SBX failed to "discriminate," mistaking falling chunks of unspent rocket fuel or other material for the target missile.

In a June 2014 test, an interceptor destroyed its target, but SBX’s "hit assessment" did not reach commanders in control of the system, according to a report by the Pentagon’s evaluation office.

In an attack, an immediate and accurate hit assessment would be crucial.

Patrick J. O’Reilly, director of the Missile Defense Agency from 2008 to 2012, explained why: Without the assessment, "the commanders could order the soldiers to shoot additional interceptors at targets that have actually already been destroyed — or to stop shooting at targets that haven’t been destroyed," he said in an interview.

O’Reilly said it was "worrisome" that commanders did not receive the hit assessment in the 2014 test.

An agency spokesman, Richard Lehner, said an investigation into the matter is "nearing closure."

——

Senior military leaders had grown disillusioned with SBX years earlier. The vessel burned millions of gallons of fuel to power the radar or move about. It had to be resupplied at sea, and wind and salt water posed unrelenting challenges for sensitive instruments.

In 2009, then-Defense Secretary Robert M. Gates canceled plans to send SBX near the Korean Peninsula to monitor the launch of a North Korean test rocket. Gates said he could not justify the mission’s cost, estimated at tens of millions of dollars.

The same year, O’Reilly decided that the radar belonged under the operational control of the Navy. "It was obviously part of a major weapon system at sea," he recalled.

The Navy’s Pacific Command insisted on extensive modifications to bring SBX up to survival standards for combatant vessels. The cost ran to tens of millions of dollars — emblematic of the floating radar’s tortuous history.

SBX was never based at its specially prepared Alaskan berth. In 2012, it was downgraded to "limited test support status."

In 2013, the radar sat idle in Pearl Harbor for more than eight months, records show.

To date, SBX has cost taxpayers about $2.2 billion, according to the Missile Defense Agency.

The government recently began seeking proposals for a new radar to help fulfill SBX’s original purpose.

It will be installed in Alaska, on land. The target date is 2020, and the estimated cost is $1 billion.