Donald Trump’s protectionist measures have sparked fears of an all-out trade war after China retaliated by imposing tariffs of up to 25 per cent on 128 US imports worth a total of $3bn.

Hours before US stock markets opened on Monday, the Chinese began enforcing the new tariffs on American imports including pork and scrap aluminium.

The possibility of a full-on trade war was also signalled by an editorial in the Global Times, a tabloid newspaper published by the Chinese Communist Party, which stated: “Even though China and the US have not publicly said they are in a trade war, the sparks of such a war have already started to fly.” 

The editorial, published hours after the tariff increases were announced, added that if the US had thought China would not retaliate or would only take symbolic countermeasures, it could now “say goodbye to that delusion”.

“American politicians better realise sooner rather than later that China would never submit if the US launched a trade war,” the editorial stated.

As well as the 25 per cent tariffs on pork and scrap aluminium, the new measures included 15 per cent tariffs on apples, and almonds, raising the possibility that farming areas, many of which voted for Trump in the 2016 presidential election, will be hit hardest by the Chinese retaliation.  

US farmers sent nearly $20bn (£14bn) of goods to China in 2017, and the American pork industry sent $1.1bn in products, making the Asian nation the world’s third largest market for US pork.

Even before the Chinese measures were announced, some US farmers in Trump-voting areas were telling The Independent about their fears of a trade war.  

Announcing its countermeasures, China’s government said the country’s imports of the 128 American products affected by the new tariffs totalled $3bn (£2.1bn) last year.

It also made clear that it was retaliating against Mr Trump’s order to impose a 25 per cent tariff on steel imports and a 10 per cent tariff on aluminium imports from 23 March.

Mr Trump has often accused China of stealing American jobs through unfair trade practices, and as he signed the tariff order he said he was fulfilling a campaign promise to the US steelworkers who had voted for him.    

Foreign leaders, however, warned that he risked starting a trade war, and China and the EU both said they would retaliate with their own import taxes against the US.

China’s retaliation also comes 11 days after Mr Trump unveiled a plan to impose up to $60bn in new tariffs on Chinese goods.

As he did so, Mr Trump again lamented “unfair” trade deals and said he had asked China to immediately reduce its trade surplus with America by $100bn. 

He also criticised the World Trade Organisation, saying it has been a disaster for the US and its arbitration had been very unfair. 

Experts, however, warned that the American moves were almost certain to provoke a powerful Chinese reaction.

Robert Ross, professor of political science at Boston College, told The Independent: “I think we are making policy as if we are still the dominant superpower in the world, but China has become a major power and a major market, and it has the ability to retaliate.”

As the Chinese government announced the new tariffs late on Sunday night, it criticised the way Mr Trump had combined his steel and aluminium measures with a promise of exemptions for “real friends” like Australia, but not for China.

China’s ministry of commerce claimed this “seriously violated” the principles of non-discrimination enshrined in World Trade Organisation rules, and also damaged China’s interests.

In linking their tariff increases to Mr Trump raising steel and aluminium duties, the Chinese have also left open the possibility that they might take further measures in response to the US president’s plan to impose up to $60bn in new tariffs.

And in an opinion article on Monday, China’s official news agency Xinhua warned that Mr Trump’s plans for these further trade measures were a “self-defeating gamble” that would cause harm to the American economy.

The article claimed: “Trump’s planned tariffs are not only going to hamper the United States’ economic wellbeing and continued progress, and burden its people with higher costs of living, but also pose a grave threat to the current global trading system.”

Forecasters said they expected the immediate impact of the current American and Chinese measures to be limited.

Investors, however, worry that the global recovery might be set back if other governments respond by raising import barriers. 

Those fears temporarily depressed financial markets, but shares appear to have recovered some of their initial losses. 

On Monday, stock market indexes in Tokyo and Shanghai were up 0.5 per cent at midmorning.