For a country as utterly dependent on electronics and electricity as the United States, it’s a nightmarish scenario.

Imagine a weapon that can disable our electrical grid, shutting down the telecommunications network and all other systems that need energy to run.

Phones wouldn’t work. Computers wouldn’t function. People wouldn’t be able to withdraw money from an ATM. Water filtration and sewage treatment plants wouldn’t operate.

“If electricity were suddenly to fail, we would be instantaneously transferred from the 21st century to the 19th century,” said Christopher

A. Beck, senior adviser for science and technology to the House Homeland Security Committee.

This may sound far-fetched, but experts say this is exactly what could happen if the United States ever experienced an attack by an electromagnetic pulse, or EMP.

And a group of congressional, military and intelligence officials warned Wednesday during a national conference in Niagara Falls that this country isn’t prepared for the EMP threat.

Skeptics, including some liberals, say that an EMP attack is highly improbable and that conservative politicians such as former House Speaker Newt Gingrich have flogged the issue in an effort to boost defense spending.

But event organizers and attendees — more than 800 people registered for the conference that continues today—say that the threat is real and that the issue can’t be ignored or trivialized any longer.

EMPs are “the greatest threat to our national security,” former Rep. Curt Weldon of Pennsylvania, known for a focus on defense issues during his 20 years in the House,

told the crowd in the Conference Center Niagara Falls.

“There’s really no excuse for this country to be vulnerable to EMP,” added Peter V. Pry, president of EMPACT America.

The EMP conference drew academic researchers, government officials, businesspeople and first responders from as far away as South Korea. Former Republican presidential candidate Mike Huckabee is scheduled to speak today, and Gingrich spoke by video Wednesday.

Sponsoring the event is Steuben Foods, whose chairman, Henry M. Schwartz, founded EMPACT America and has embraced the EMP issue. He is working to convince local officials of the importance of preparing for such an attack, and he is investing in measures to protect Steuben’s Elma facility from EMPs.

“We think we can get a movement started in Western New York,” Schwartz told The Buffalo News in an interview.

EMPs have been identified as a potential weapon and threat for decades. But they’ve largely remained the stuff of science fiction, used in the plots of films including “Ocean’s 11.”

Both the United States and the Soviet Union had the ability to launch an EMP attack, which likely would involve the detonation of a nuclear device at a high altitude.

The explosion would send out electromagnetic pulses that could wreak havoc over a wide area, rendering inoperable any electronic devices or networks that rely on electricity to function. Nonnuclear devices can create EMPs on a smaller scale, experts said, as can natural phenomena such as geomagnetic storms.

Naysayers argue that the threat of an EMP attack is remote, with the New Republic magazine’s Michael Crowley calling it “scientifically valid” but “not strategically realistic.”

Experts at the conference warned that an EMP attack could happen and that it would be even more harmful today than at the height of the Cold War.

“Today, our society is totally reliant on computers. It’s our No. 1 vulnerability,” Weldon told The News in an interview.

EMPs are particularly attractive to enemy combatants and rogue states such as Iran and North Korea that have the ability to launch missiles at great distances, speakers said.

“We would, in fact, basically lose our civilization in a matter of seconds,” Gingrich said in his video. “This wasn’t made up out of whole cloth. It is a very real and very direct threat to our country.”

So what can be done to protect against EMPs?

Speakers at the conference said the United States needs to invest more in research and in protecting vulnerable parts of the electrical infrastructure.

A congressional commission issued a set of recommendations to that end earlier this decade, but most have not been implemented, said experts at the conference, including several members of the commission.

Speakers suggested that conference attendees contact their federal elected officials to urge them to support EMP legislation.

“I certainly hope that this conference can get the focus back on EMP” as a strategic security threat, said retired Adm. William O. Studeman, a longtime defense intelligence official.

At least one speaker, Beck, acknowledged that people who are passionate about the EMP issue are sometimes viewed as being a little off-kilter, but he said the good turnout at the conference shows that they are not alone.