Kim Hjelmgaard

USA TODAY

LONDON — The United Kingdom's break with the European Union is an unprecedented "political earthquake" that sweeps away decades of diplomatic harmony and unravels a post-World War II dream of a unified voice to guarantee peace, economic prosperity and security.

After 43 years in European coalitions, the U.K. is parachuting out of a 28-nation bloc that is riven with divisions over the refugee crisis, weighed down with the Greek debt drama and relatively powerless in the face of Russian aggression in Ukraine. The EU is also weathering populist, far-right revolts among large swaths of its 500 million citizens in France, Hungary, the Netherlands, Poland.

EU leaders say 'Brexit' should be ASAP

'Brexit' generation split visible at Glastonbury Festival

"People who watched the British vote will no doubt get the impression that the EU does not really work," said Michael Wohlgemuth, director of the Berlin office of Open Europe, a think tank that specializes in European affairs. "From the outside, it does not appear to be an efficient organization. They'll wonder how it can prevail in the long run."

He said all the confusion in the U.K. "is not really providing a great model for other EU countries to follow. It needs to focus on reforms that bring benefits to its citizens."

To be sure, the EU is not in danger of immediately disintegrating, but losing the U.K. as a member nation will be a "considerable blow to the prestige and credibility" of the alliance, said Maxime Henri Andre Larive, associate director of the European Union Center at the University of Illinois at Urbana-Champaign.

"It was until (Thursday's referendum) a club where exiting was not even a consideration. It is now a reality and option" and may lead to further defections, Larive said. "Brexit (or British exit) is an unprecedented scenario that should be interpreted as a political earthquake. The EU is in uncharted waters and needs to reflect seriously about its future."

The Brexit victory results of 52% to 48% was a surprise after polls forecast a narrow win for the "remain" side. The battle lines were drawn over the issues of immigration and the economy. "Leave" voters want fewer immigrants coming here. The "remain" side said life outside the EU would jeopardize Britons' living standards.

Heartbreak for London's pro-EU crowd

The outcome has thrown the country into a period of extreme uncertainty. The British pound plummeted. Prime Minister David Cameron announced he will resign by October. Scotland, which voted to stay in the EU, will almost certainly hold a second independence referendum to sever it from the U.K. There's also a possible move by Irish nationalists to push for a united Republic of Ireland and Northern Ireland.

The U.K. is now split emotionally as droves of alienated "remain" supporters struggle with saying farewell to the European alliance that was created to overcome the poisonous nationalism that contributed to two world wars and millions of deaths.

Considerable anger is directed at Cameron. Although the prime minister fought hard to keep the country in the EU, he agreed to a referendum last year in a campaign promise to quell a threatened rebellion from Euro-skeptic members of his own Conservative Party. It now looks like he put his career above country.

"Britain cannot leave Europe any more than Piccadilly Circus can leave London. Europe is where we are, and where we will remain," Timothy Garton Ash, a professor of European studies at Oxford University, wrote in a mournful essay in Saturday's Guardian newspaper. "A universal truth: Nobody knows what it going to happen but everyone can explain it afterward."

While the Brexit vote reflects discontent with the EU in the U.K., there is also grumbling from other member nations after years of what critics say is onerous legislation from the alliance. EU legislation governs a range of issues from exports to workers' rights to fishing ground treaties.

According to the Pew Research Center, several countries want some EU power returned to their national governments: a majority in Greece (68%) and pluralities in the Netherlands (44%), Germany (43%), Italy (39%) and France (39%).

Matthew Goodwin, a professor of international relations at the University of Kent, said Brexit is not the beginning of the end for the EU.

"But it's facing it's next major challenge — public legitimacy," he said.