WASHINGTON, May 19 (UPI) — President Donald Trump’s move to build a national missile defense system would leave millions of Americans vulnerable to nuclear attack despite the program’s exorbitant cost, the author of a new scientific report said at a press conference Tuesday outside the U.S. Capitol.

The report simulated a “best case scenario” in which the Golden Dome system shot down 80% of incoming missiles, said Ira Helfand, the report’s main author and a co-founder of Physicians for Social Responsibility, an anti-nuclear weapons organization.

Under those circumstances, more than 300 warheads still would reach the United States, the report found, and that Russia would have a 95% chance of being able to destroy any one of 132 major population centers in which a combined 75 million Americans live.

“Let’s be clear what Golden Dome is: a vanity project of one person, Donald Trump,” said Rep. Jim McGovern, D-Mass., using Trump’s chosen moniker for the missile defense system. McGovern was one of two Massachusetts lawmakers who led the press event.

“We must suffer the Trump arch, the Trump ballroom, the Trump battleship and now Trump’s Golden Dome. Each are the egotistical fantasies of an aging man who needs psychiatric care,” McGovern said.

Soon after taking office in 2025, Trump directed the Defense Department to develop a homeland air and missile defense system. The order called for protecting the U.S. “against ballistic, hypersonic, advanced cruise missiles and other next-generation aerial attacks from peer, near-peer and rogue adversaries.”

This initiative, later named Golden Dome for America, echoes earlier missile defense efforts, such as President Ronald Reagan’s Strategic Defense Initiative, commonly known as Star Wars. It was never fully built or deployed.

“Building an effective and reliable shield against any realistic attack by nuclear-armed ICBMs is technologically infeasible for the foreseeable future,” said Laura Grego, a physicist who specializes in nuclear security at the Union of Concerned Scientists.

“But also attempting to build one would be hugely expensive — wasting time and resources — and accelerate the nuclear arms race.”

The report was released by the Nobel Peace Prize-winning International Physicians for the Prevention of Nuclear War, Physicians for Social Responsibility and Back from the Brink, all advocates for abolishing nuclear weapons.

The press conference came after a Congressional Budget Office report released last week found that a missile defense system designed to counter a small-scale nuclear attack would cost $1.2 trillion.

A more robust system in line with Trump’s aspirations of “ending the missile threat to the American homeland,” would come with a $3.6 trillion price tag, according to a 2025 estimate by the American Enterprise Institute, a right-of-center think tank. Trump initially offered a price tag of $175 billion for the project.

“The Golden Dome is fool’s gold,” said Sen. Ed Markey, D-Mass. “It’s a gold-plated boondoggle that will enrich defense contractors and ignite a new nuclear arms race.”

Rep. Austin Scott, R-Ga., who sits on the House Armed Services Committee, told Medill News Service that he did not agree with the report’s conclusion that the Golden Dome would be too ineffective and costly to justify. On the contrary, Scott said, nuclear modernization efforts underway by U.S. rivals required a response.

“The weapons coming from China and Russia are faster and stronger,” Scott said. “And we have to be able to pick them up faster.”

Between 2014 and 2024, the estimated number of Chinese nuclear warheads doubled, from 250 to roughly 500, according to the China Power Project at the Center for Strategic and International Studies.

China, however, has maintained a no-first-use policy since it first detonated a nuclear weapon in 1964, which commits Beijing to only employ its nuclear weapons in response to a nuclear attack by another country.

When asked about claims made by Helfand and others at the press conference that the Golden Dome would spur a new global nuclear arms race, Scott disagreed again.

“It’s a defensive system,” he said, “not an offensive system.”

The planned outlays for the Golden Dome come in tandem with other Trump administration priorities that have raised eyebrows on Capitol Hill, including a $1.5 trillion defense spending package for 2027, $400 million for a new White House ballroom that will sit atop a bunker and $29 billion so far for the war in Iran.

At the same time, in its proposed budget, the White House moved to cut non-defense discretionary spending by 10%. The spending category comprises public health, scientific research and scores of other domestic programs.

At Tuesday’s press conference, Markey said the United States doesn’t have trillions of dollars to waste on a system that “is not going to protect the American people,” and he decried funding cuts to social programs that “actually do provide security for families in their own homes.”