By John Sudworth
BBC News, Seoul
Protestors have numbered 20,000 who object to US beef imports
Many people are wondering how it could have come to this.
Not least South Korea's President, Lee Myung-bak, who, just 100 days into office has shown he has the opposite of the Midas touch.
The landslide popularity that brought him to power has evaporated, the more humiliating opinion polls put his support rating barely into double digits.
A once seemingly mundane and long running agricultural dispute has mushroomed into one of the biggest political crises in recent memory.
It is a crisis that has taken shape on the streets.
What started as a series of relatively small-scale candlelit vigils against a lifting of the five-year ban on American beef imports, has now taken on the air of a mass movement.
Mothers pushing prams march alongside ranks of high-pitched school children, all carrying delicate, fluttering flames through the dark Seoul night.
The symbolism is potent. It is a picture of the nation's most cherished and vulnerable under threat from a cavalier government and the poisoned, imported produce of a foreign power.
"I am afraid of American beef," one 13-year-old protester told a US newspaper reporter. "I could study hard in school. I could get a good job and then I could eat beef and just die."
This week, the growing intensity of the protests and sporadic outbreaks of violence finally forced a government U-turn.
The lifting of the ban on US beef has been put on hold.
"The essence of the beef protests is anti-American," said Keun Park, President of the Korea-America Friendship Society.
"The left-wing media has instigated the feeling that there is a good reason to fear US beef."
Some of the claims made about the risks of mad cow disease are certainly difficult to substantiate.
Young mothers and children say they are afraid to eat US meat
South Korea's marching citizens have been worried onto the streets by widely circulated rumours that American consumers do not eat beef from cattle aged over 30 months, and that large quantities of this more dangerous, older meat will flood into Korea.
It was with reference to these fears that the South Korean government suspended the import agreement this week, saying it wanted 30-month and older cattle removed from the deal.
But according to statistics from the US beef industry, 18% of cattle slaughtered in the US for human consumption is above, in many cases well above, 30 months of age.
The meat from these animals, considered perfectly safe, is ground into beef for burgers and other such delights.
Americans, it seems, do not just eat 30-month-old cows, they eat them in vast quantities.
And according to Joe Schuele from the US National Cattlemen's Beef Association, "research shows that before exports were stopped in 2003, less than 2% of the total beef we sent to South Korea came from cattle aged over 30 months".
It is hardly a flood.
Among the more hysterical claims, of course, the fears of many South Koreans about the safety of imported beef are genuinely held.
After all, there are those in the US, both producers and consumers, who argue that there should be much more testing of slaughtered cattle than there is at present.
But central to the South Korean government's willingness to open its ports is the certification of US beef hygiene standards by the World Organisation for Animal Health.
According to this intergovernmental food-safety body, the US removes risky material from slaughtered animals, conducts adequate testing and has feed policies that control the risk and make its meat safe for export.
South Korea has yet to supply enough information to the World Organisation for Animal Health to allow an assessment of its own mad cow risk to be carried out.
Hahm Sung-deuk, professor of presidential studies at Korea University, did not agree that the beef protests were motivated by anti-American sentiment, but he admitted that outsiders may well be baffled as to why it has become such a serious issue.
"People have become gradually disappointed with President Lee," he said. "There have been a series of errors."
One of the biggest ones, he said, was to give the appearance of capitulating to American political interests.
Free-trade deal risked
Politicians in Washington were threatening to scupper a US-South Korea free-trade deal - one that President Lee is championing - unless he gave them back what used to be America's third largest market for beef exports.
That he duly obliged, seemingly without consultation and with the agreement to include almost all beef products, of all ages, may have proved the catalyst for the rising public anger.
South Korea's political leadership has been caught out by the uproar
"People felt that this guy was just out of touch," Professor Hahm added. "Now the US needs to come to his assistance."
The Americans however seem reluctant to drop cattle aged over 30 months from the agreement, although some might ask why, given that these older animals make up such a small share of the export market.
Not all South Koreans agree with the candlelit protesters who continue to march through the streets of Seoul each night.
Lee Sae Jin, a 25-year-old university student, bravely held his own, one-man protest in favour of US beef imports.
He was soon shepherded away by a policeman, led off through the rather angry crowd that had gathered to read his posters.
"We are an exporting nation," he had written.
"We are creating the fear of mad cow disease in our own minds. Candlelights should be used to brighten the darkness, not burn down our own homes."