China used the United States' "own free press" to bully American workers, farmers and businesses over trade, Terry Branstad, the U.S. ambassador to China, wrote in an op-ed that appeared in the Sept. 30 Des Moines Sunday Register.

The four-page China Daily advertising supplement that ran in the Register a week ago "doubles down" on Chinese retaliation against the U.S. for fighting against Beijing's "unfair trade policies," Iowa's former governor says.

China has slapped tit-for-tat tariffs on $250 billion of U.S. goods in response to American duties that began this spring.

"Unfortunately, China has responded to such action by taking further steps to harm American workers, farmers and businesses through retaliatory actions — and is now doubling down on that bullying by running propaganda ads in our own free press," Branstad writes.

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But the Trump administration placed a “large bull's-eye” on U.S. farmers by failing to get Europe, Japan and other developed countries to join America in challenging China’s trade practices, said Tom Vilsack, also a former Iowa governor.

“It’s not that administration is wrong about raising issues,” said Vilsack, CEO of the U.S. Dairy Export Council. But the “approach that they’ve taken essentially created a fairly large bull's-eye on American agriculture” because of its trade surplus with China.

“The reality is that other countries are being treated in the same, unfair way,” he said. “If other countries would have joined us, it would have been difficult for China to retaliate against all agriculture internationally.

“We’ve created the opportunity for them to go into Europe, South America and other countries to get products we’ve been providing them,” said Vilsack, who served as the U.S. ag secretary under former President Barack Obama.

Branstad writes in his op-ed that the Chinese have "a sustained campaign to acquire our technologies and intellectual property through practices ranging from forced technology transfer and the evasion of export controls to outright theft through cyber-enabled means and traditional spycraft."

"Many Iowans remember the case in which a Chinese agent attempted to literally steal the seed corn from our fields," he writes, referring to a yearslong conspiracy involving several Chinese citizens who sought to smuggle valuable patented corn seeds to a Chinese agriculture conglomerate.

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Mike Naig, Iowa's agriculture secretary, said farmers understand China's trade barriers. "We talk a lot about issues with biotech trait approval, blocking corn and DDGs and ethanol, beef and poultry," said the Republican, who's making his first run for the office after being appointed to the post in March.

Distiller's dried grain (DDG) is a high-protein ethanol byproduct that's fed to livestock.

"Farmers recognize that something needs to be done," said Naig, the state's deputy ag secretary for five years. "But we're no fan of tariffs. ... They're absolutely impacting our markets and hurting farmers."

Tim Gannon, the Democrat running against Naig, said the Trump trade disputes are "taking money out of farmers' pockets. And the way farming has been, there's no extra money to give up."

The escalating trade war has slammed U.S. farmers, manufacturers and other industries.

Iowa farmers face a $2.2 billion trade hit that's expected to ripple through the economy and cut state tax receipts by $110 million, a recent Iowa State University study found.

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Branstad's opinion piece came days after his boss, President Donald Trump, pointed to the paid advertorial as evidence that Beijing is trying to interfere in the U.S. midterm elections.

► RELATED:Citing Register ad, Trump says China meddling in U.S. elections

“Regrettably, we found that China has been attempting to interfere in our upcoming 2018 election, coming up in November, against my administration,” Trump said at a meeting of the United Nations' Security Council on Wednesday.

The president later specifically cited the China Daily advertising supplement that ran in the Sunday Register on Sept. 23.

"China is actually placing propaganda ads in the Des Moines Register and other papers, made to look like news. That’s because we are beating them on Trade, opening markets, and the farmers will make a fortune when this is over!" the president tweeted.

The China Daily insert touted the mutual benefits of U.S.-China trade, built on concern about long-term market losses, and highlighted President Xi Jinping's three-decades-long relationship with Iowa.

That relationship includes a close friendship between Xi and Branstad.

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Donna Hoffman, a University of Northern Iowa political science professor, questioned whether the insert rose to the level of election interference.

"People might think it’s unsavory, but I don’t think ... China is trying to influence the U.S. elections," she said. "Trump made a leap from point A to point G."

Gannon, who farms with his family near Mingo, said Trump made a mistake starting trade disputes with several longtime partners.

"It's easier to win a basketball game if you're playing one on one, instead of five on one," said the Democrat, who worked for eight years with Vilsack at the U.S. Department of Agriculture.

"We’re settling in for a protracted game of 'who will flinch first,'" Gannon said. "That’s not good for farmers. We’re bearing the brunt of this."

Branstad wrote that the "Trump administration is putting America and Americans first by calling on China to live up to its pledge when it joined the World Trade Organization in 2001.

"It is simply unsustainable for the world’s second-largest economy to ignore or dismiss fundamental precepts of free and fair trade, while the United States and the rest of the world are forced to pay the price for China’s misguided and adversarial economic policies," Branstad said.

Mark Jackson, who farms near Oskaloosa, said the Trump administration deserves credit for tackling the U.S.’s $376 billion trade deficit with China.

China is “the bad player in this conversation … not the Trump administration,” said Jackson, who raises corn, soybeans, beef and pork with his brother and son.

Still, Jackson said Iowa farmers — many of whom supported Trump in the 2016 election — are concerned about falling soybean, pork and other commodity prices, as well as the possible long-term loss of China's market.

China is the largest buyer of U.S. soybeans and second-largest buyer of pork, based on weight. Iowa is the nation's largest pork producer and second-largest soybean producer.

“We’re definitely in a pinch,” Jackson said, adding that the federal government’s $12 billion federal aid package for farmers will help.

The first round will send $4.7 billion directly to soybean, pork, dairy, cotton and other growers. Iowa farmers expect to see $550 million.

Vilsack said Trump's administration has argued that it's farmers' "patriotic responsibility and duty to step up and take one for the team."

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But "this is about business. It’s not about patriotism," Vilsack said.

"It’s not about asking China to buy more stuff. Because that would be easy for them to do," he said. "It's really about them changing the nature and structure of how they let investment into their country — that's a pretty big deal.

"This is going to last a while, and that's my deepest concern for agriculture," Vilsack said.

Dairy producers, for example, will lose $12 billion in sales if the trade dispute lasts five more years.

"When and if this thing gets resolved, it might be a long, long time to get the market share we had before" for soybeans, pork and other products, he said.

"That's going to be tough. ... The assistance program compensates you for one crop year — not multiple years that your income might be impacted," Vilsack said.