Cold War-era critics of President Reagan’s “Star Wars” idea are back, with Communist China, Russia, and North Korea slamming President Trump’s plan to shield America under a Golden Dome. 

Foreign foes are joined by home critics who contend that Mr. Trump’s bling edition of Israel’s Iron Dome would only exacerbate a global arms race, that it would launch outer space wars, and that the idea of shielding the country from enemy attack is unrealistic.

Similar arguments sounded out in the early 1980s, when Reagan launched the Strategic Defense Initiative, which was widely ridiculed as an unworkable “Star Wars”-inspired fantasy.

“The comparison is a very good one,” a senior fellow at the Center for Security Policy, Colonel Grant Newsham, tells the Sun from Seoul. “That response is what you always hear whenever the Americans in the free world try to defend themselves, and you will even hear people on our side make it.”

When SDI was introduced in March 1983, the concept challenged the Cold War’s dominant arms-control theory, which argued that Mutually Assured Destruction would prevent a nuclear exchange between the superpowers. In 1986 Reagan famously walked out of a summit at Reykjavik after the Soviet Union’s secretary general, Mikhail Gorbachev, demanded he drop the program.    

At the time, “allies and opponents of the United States were suddenly united in their opposition to this new concept,” a former British attache in Washington, Stanley Orman, writes.   

“That same criticism came up when we were doing very little on missile defense in the 2010s,” a fellow with the missile defense project at the Center for Strategic and International Studies, Masao Daghlen, tells the Sun. At that time a “minimal deployment of missile defenses to Romania elicited a similar response as this more ambitious plan,” Mr. Trump’s Golden Dome.  

The plan, involving complex components such as space-based sensors, would be operational before Mr. Trump leaves office, the president said when he introduced it last Tuesday. “Once fully constructed, the Golden Dome will be capable of intercepting missiles even if they are launched from other sides of the world, and even if they are launched from space,” he said. 

As if on cue, America’s foes launched a seemingly coordinated rhetorical assault. The plan is “very dangerous,” Pyongyang’s foreign ministry said in a statement Tuesday, adding that the Golden Dome is an “outer space nuclear war scenario supporting the U.S. strategy for unipolar domination.”

It represents “a direct disruption to the foundations of strategic stability,” Moscow’s foreign ministry spokeswoman, Maria Zakharova, told reporters Tuesday. In an earlier joint statement, Russia and Communist China called the Golden Dome “deeply destabilizing,” and claimed it will turn outer space into a ”warfighting domain.”

In 2018 Moscow introduced a new generation of low-flying projectiles that travel five times the speed of sound, known as hypersonic missiles. “Missile-defense systems are useless against them, absolutely pointless,” President Putin said as he presented his new weapon. Communist China is leading the hypersonic missile race, and North Korea possesses some that could hit America. 

“Hypersonic weapons are a major challenge,” the CSIS’s Mr. Daghlen says. “They fly significantly lower than ballistic missiles, so you don’t see them come over the earth’s horizon until quite soon.” To fill the gap, he says, sensors need to be placed in space, and America has already launched eight prototypes. “What interceptor you have is a number one priority,” he says. “I think it was right for this program to want that priority accelerated.”

Critics, though, contend that Mr. Trump’s program is a dangerous and costly fantasy. “Intercepting even a single, nuclear-armed intercontinental-range ballistic missile or its warheads is extremely challenging,” a University of Illinois physicist, Frederick Lamb, said recently. “The ability of any missile defense system to do this reliably has not been demonstrated,” he added, introducing a critical report by the American Physical Society. 

A similar critique — that millions of people will die even if one nuclear-armed missile evades “Star Wars” — was prevalent in the 1980s. The SDI program indeed disbanded in 1993, but not before it helped catalyze the Soviet Union’s collapse and introduced a new concept in modern warfare. 

America developed the Patriot anti-missile program, which now helps defend Ukraine, including by intercepting Russian weapons with similar characteristics to hypersonic missiles.  These — and the Iron Dome, David’s Sling, and Arrow systems that are protecting Israelis from endless missile attacks — are derivatives of Reagen’s vision, even if not exactly what he foresaw in the 1980s. 

Now that America’s foes are developing “hypersonics, fractional orbital bombardment systems, we need something,” Colonel Newsham says. “So it may not be this 100 percent Golden Dome as Trump sees it, or his advisors see it, but it will move things farther along than would otherwise be the case.”