WASHINGTON (Reuters) - Last week, President Donald J. Trump chose the deck of the newest U.S. aircraft carrier, the $13 billion USS Gerald R. Ford, for a speech extolling his planned boost in military spending.

Trump vowed that the newest generation of “Ford Class” carriers - the most expensive warships ever built - will remain the centerpiece of projecting American power abroad.

“We’re going to soon have more coming,” Trump told an enthusiastic audience of sailors, declaring the new carriers so big and solidly built that they were immune to attack.

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Trump vowed to expand the number of carriers the United States fields from 10 to 12. And he promised to bring down the cost of building three “super-carriers,” which has ballooned by a third over the last decade from $27 to $36 billion.

The Gerald R. Ford alone is $2.5 billion over budget and three years behind schedule, military officials say. The second Ford-class carrier, the John F. Kennedy, is running five years late.

Trump’s expansion plans come as evidence mounts that potential enemies have built new anti-ship weapons able to destroy much of the United States’ expensive fleet of carriers. And as they have been for decades, carriers remain vulnerable to submarines.

In a combat exercise off the coast of Florida in 2015, a small French nuclear submarine, the Saphir, snuck through multiple rings of defenses and “sank” the U.S. aircraft carrier Theodore Roosevelt and half of its escort ships. In other naval exercises, even old-fashioned diesel-electric submarines have beaten carriers.

All told, since the early 1980s, U.S. and British carriers have been sunk at least 14 times in so-called “free play” war games meant to simulate real battle, according to think tanks, foreign navies and press accounts. The exact total is unknown because the Navy classifies exercise reports.

Today, the United States is the only country to base its naval strategy on aircraft carriers. The U.S. fleet of 10 active carriers is 10 times as big as those deployed by its primary military rivals, Russia and China, who field one active carrier each.

Roger Thompson, a defense analyst and professor at Kyung Hee University in South Korea, says the array of powerful anti-ship weapons developed in recent years by potential U.S. enemies, including China, Russia and Iran, increase carriers’ vulnerability.

The new weapons include land-based ballistic missiles, such as China’s Dong Feng-21 anti-ship missile, which has a claimed range of 1,100 miles (1,770 kilometers) and moves at 10 times the speed of sound. Certain Russian and Chinese submarines can fire salvoes of precision-guided cruise missiles from afar, potentially overwhelming carrier-fleet anti-missile defense.

Russia, China, Iran and other countries also have so-called super-cavitating torpedoes. These form an air bubble in front of them, enabling them to travel at hundreds of miles per hour. The torpedoes cannot be guided, but if aimed straight at a ship they are difficult to avoid.

A 2015 Rand Corporation report, “Chinese Threats to U.S. Surface Ships,” found that if hostilities broke out, “the risks to U.S. carriers are substantial and rising.”

“Beyond a shadow of a doubt, a carrier is just a target,” says defense analyst Pierre Sprey, who worked for the U.S. Secretary of Defense’s office from 1966 to 1986 and is a longtime critic of U.S. weapons procurement.

DEFENDING CARRIERS

Navy leaders stand by the carrier. In an interview late last year, Admiral Scott Swift, commander of the U.S. Pacific Fleet, lauded carriers’ versatility. Swift says they remain “very viable,” sufficiently impregnable to be sent into the thick of combat zones.

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Swift said he would order carriers into close battle “in a heartbeat.” Nevertheless, citing the new anti-ship weapons, Swift says the carrier “is not as viable as it was 15 years ago.”

Trump has said he will make good on his campaign promise to increase the Navy’s fleet to 350 ships. The Navy currently has 277 deployable ships. The cost of a single new, Ford-class carrier – $10.5 billion without cost overruns – would consume nearly 20 percent of Trump’s proposed $54 billion increase in next year’s defense budget.

Some critics, including former senior Defense Department personnel, say Washington has put too much of the country’s defense budget into a handful of expensive, vulnerable carriers.

At a naval symposium in 2010, then-Secretary of Defense Robert Gates called into question making such big investments in a few increasingly sinkable ships. Gates said “a Ford-class carrier plus its full complement of the latest aircraft would represent potentially $15 billion to $20 billion worth of hardware at risk.”

The Navy, with the backing of Congress, went ahead nevertheless. The program has strong Congressional backing. In the 1990s, when defense spending was cut after the end of the Cold War, Congress enacted a law requiring the Navy to maintain an 11-carrier fleet.

Congress has given the Navy a temporary exemption to have 10 active carriers while one is overhauled. When the Ford is commissioned, it will bring the U.S. carrier fleet to 11.

Trump did not specify in his speech how he would bring the carrier fleet to 12. But he said the Ford-class carriers would be invulnerable to attack because they represent the best in American know-how.

“There is no competition to this ship,” declared Trump, who called the Gerald R. Ford American craftsmanship “at its biggest, at its best, at its finest.”

FAILING SYSTEMS

Trump did not mention that the ship’s builder, Huntington Ingalls Industries, launched the Ford more than three years ago, but the Navy has yet to commission it and put it into service because of severe flaws. Many of its new high tech systems failed to work, including such basic ones as the “arresting gear” that catches and stops landing jets.

The Navy says the ship will be commissioned sometime this year. But the criticism has continued.

In a written statement in July, John McCain, chairman of the Senate Armed Services Committee, noted the cost overruns and cited a list of crucial malfunctioning systems that remained unfixed. “The Ford-class program is a case study in why our acquisition system must be reformed,” McCain wrote.

Ray Mabus, who in January stepped down as secretary of the Navy, said in an interview that the Gerald R. Ford “is a poster child for how not to build a ship.” He added: “Everything that could have been done wrong was done wrong.”

Mabus said that because of commitments made before he became Navy secretary, the Ford was loaded with high-tech equipment that had not even been designed yet. He also faulted awarding the shipbuilder a “cost plus” contract, under which it gets a fixed profit regardless of how much it costs to build the vessel. “There was no incentive to hold down costs,” Mabus said.

Others criticize carriers as strategically flawed. Jerry Hendrix, a retired Navy captain and Defense Department official, is now director of the Defense Strategies and Assessments Program at the Center for a New American Security. Carriers, he said in an email exchange, give Washington’s rivals a cheap opportunity to score big. For the cost of a single carrier, he calculates, a rival can deploy 1,227 anti-carrier missiles.

“The enemy can build a lot more missiles than we can carriers for equivalent investments,” Hendrix said, “and hence overwhelm our defensive capabilities.”

The most commonly proposed alternative to carriers is building a much larger number of smaller, nimbler vessels, including submarines and surface ships. Submarines don’t require escorts and can hit distant targets on land. And carriers have not been tested in battle against an enemy able to fight back since World War II – more than 70 years ago.

The Navy and some outside defense experts say that despite increased threats, carriers remain fully viable and perform an essential service. They laud carriers’ mobility and swiftness, enabling the United States to project air power to places otherwise unreachable.

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Carrier proponent Bryan McGrath, the deputy director of the Hudson Institute’s Center for American Seapower in Washington, said carriers are less vulnerable than stationary, land-based air bases.

“A carrier is a big floating airport, and not only a floating airport, but it moves at 40 knots,” says McGrath, a former captain of a guided missile destroyer. “How much more vulnerable are airfields on land that don’t move?”

But Sprey, the former Defense Department official and longtime Pentagon procurement critic, says carriers waste funds that could be used to build more cost-effective weapons systems.

“Every Ford-class carrier we build detracts from U.S. defense,” Sprey said.

LIMITED PROTECTION

Both strong supporters of carriers as well as opponents agreed that there is a serious flaw in the current configuration of U.S. carriers: their complement of strike aircraft. Almost all are short-range jets, the F-18 Hornet, whose range could render the planes useless in some conflicts.

The Chinese, in particular, have established sea zones bristling with anti-ship weapons meant to make it impossible for enemy flotillas to enter.

Top U.S Navy commanders, including Pacific commander Swift and Vice Admiral Mike Shoemaker, the Navy “Air Boss” in charge of carriers, say carriers could safely enter such zones long enough to carry out a mission. But many outside analysts say a U.S. president would be hesitant to risk such an expensive ship and the lives of up to 5,500 crew members.

In order to be relatively safe, a carrier would have to stand off by 1,300 nautical miles, or 2,300 kilometers – out of range of the Dong Feng missiles. And the F-18s have a range of only 400 nautical miles (equal to 460 statute miles or 740 kilometers) to a target with enough fuel to return.

Experts on both sides of the debate say that if the carriers have to stand off, the Hornets would have to be refueled in midair an impractical number of times while flying to and from their targets. It thus would be all but impossible for carriers to send air power into war zones.

The F-18s are to be replaced by 2020 with new F-35C Lightning IIs, but these have only a marginally better range of 650 nautical miles.

The Hudson Institute’s McGrath, who champions carriers, says the short-range jets impair the mission.

“What they (the Navy) haven’t done yet is to design and fund a strike aircraft that can fly 1,000 miles, drop its bombs and come home,” McGrath said.

The cost of carriers in terms of strategy and money is multiplied because carriers do not travel alone. For protection, they move with large escorts, making every “carrier strike group” a virtual armada.

Each carrier usually has an escort of at least five warships, a mixture of destroyers and cruisers, at least one submarine and a combined ammunition-supply ship and helicopters designed to detect subs. When close enough to shore, carriers are also protected by new, land-based P-8 Poseidon jets, designed to detect and destroy subs.

OLD THREATS

For carrier commanders, the most feared weapon is a 150-year-old one. A single, submarine-launched torpedo could send a carrier to the bottom.

Most modern torpedoes aren’t targeted to hit ships. Instead they are programmed to explode underneath. This creates an air bubble that lifts the ship into the air and drops it, breaking the hull.

For decades, critics have faulted the Navy for failing to develop effective defenses against modern torpedoes. A 2016 report by the Pentagon’s Office of Operational Test and Evaluation said the Navy has recently made significant progress, but the systems still have crucial deficiencies.

Experts also say that carriers are at risk from updated versions of one of the oldest naval vessels still in use: the diesel-electric submarine. These were the subs used in both World Wars.

Diesel-electric subs have the advantage of being small – and while on electric power, silent, and in general quieter and harder to detect than nuclear subs.

Diesel-electric subs are also far cheaper to build than nuclear ones. Allies and rivals have been building large numbers of them. Worldwide, more than 230 diesel-electric subs are in use. China has 83 in use, while Russia has 19.

Hendrix, the former Defense Department official, says the carriers’ vulnerabilities make the fleet a profligate use of money, vessels and aircraft.

“We have paid billions of dollars to build ships that are largely defensive in their orientation, thus taking away from the offensive power of the fleet,” Hendrix says. “In the end, we spend a lot of money on defense to send 44 strike aircraft off the front end of a carrier.”