The US and China slapped tit-for-tat duties on $34 billion worth of the other's imports today.
Beijing has accused Washington of triggering the "largest-scale trade war" ever in a sharp escalation of their months-long conflict.
Hours before Washington's deadline for the tariffs to take effect, US President Donald Trump upped the ante, warning that the US may ultimately target over $500 billion worth of Chinese goods.
This is roughly the total amount of US imports from China last year.
China's commerce ministry, in a statement shortly after the US deadline passed earlier this morning, said it was forced to retaliate, meaning $34 billion worth of imported US goods including cars and agricultural products also faced 25% tariffs.
But an ensuing three-plus hour delay before Beijing confirmed that it had implemented retaliatory tariffs sowed confusion in markets.
"After the United States unfairly raised tariffs against China, China immediately put into effect raised tariffs on some US goods," foreign ministry spokesman Lu Kang told a daily media briefing today.
China's soymeal futures fell more than 2% today before recovering most of those losses, amid market uncertainty over whether China had implemented tariffs on a list of US goods, including soybeans.
Some Chinese ports had delayed clearing goods from the US, according to four sources today.
There did not appear to be any direct instructions to hold up cargoes, but some customs departments were waiting for official guidance on imposing added tariffs, the sources said.
Ford said yesterday that for now, it will not hike prices of imported Ford and higher-margin luxury Lincoln models in China.
An analysis of over four dozen imported US products facing higher duties showed that prices were little changed today compared to earlier in the week.
The products, all sold on Chinese e-commerce platforms, ranged from pet food to mixed nuts and whiskey.
While Chinese state media have slammed Trump's protectionism and likened his administration to a "gang of hoodlums," the trade conflict has gained little traction on China's tightly controlled social media, not cracking the 50 top-searched topics on the Twitter-like Weibo platform.
But the dispute has hit financial markets including stocks, currencies and the global trade of commodities from soybeans to coal in recent weeks.
Chinese shares, which have been battered in the run-up to the tariff deadline, reversed earlier losses to close higher, but the yuan remained weaker against the dollar. Asian equities wobbled but also managed to end higher in earlier trade.
In the run-up to today's tariff implementation, there was no sign of renewed negotiations between US and Chinese officials, business sources in Washington and Beijing said.
China's commerce ministry called the US actions "a violation of world trade rules" and said that it had "initiated the largest-scale trade war in economic history."
Trump has railed against Beijing for intellectual property theft and barriers to entry for US businesses and a $375 billion US trade deficit with China.
"You have another 16 (billion dollars) in two weeks, and then, as you know, we have $200 billion in abeyance and then after the $200 billion, we have $300 billion in abeyance. Ok? So we have 50 plus 200 plus almost 300," Trump told reporters on board Air Force One yesterday.
While the initial volley of tariffs was not expected to have major immediate economic impact, the fear is that a prolonged battle would disrupt makers and importers of affected goods in a blow to global trade, investment and growth.
"For companies with supply exposure to tariffs, they will move sourcing country of origin if they can; if they can't, they'll pass on as much of the tariff cost as they can, or see a cut in margins," said Jacob Parker, vice president of China operations at the US-China Business Council in Beijing.
A China central bank adviser said the planned US import tariffs on $50 billion worth of Chinese goods - $34 billion plus a planned follow-on list worth $16 billion - will cut China's economic growth by 0.2 percentage points, although the overall impact would be limited, the official Xinhua news agency said today.
US Customs and Border Protection officials were due to collect 25% duties on a range of products including motor vehicles, computer disk drives, parts of pumps, valves and printers and many other industrial components.
China's tariffs on hundreds of US goods include top exports such as soybeans, sorghum and cotton, threatening US farmers in states that backed Trump in the 2016 election, such as Texas and Iowa.
Russia raises tariffs on some US goods
Russia today raised import tariffs on some US goods in response to similar moves by Washington, the economy ministry said.
"The compensation measures are being taken in the form of additional, increased rates of import duties from 25-40% depending on the import product," Economy Minister Maxim Oreshkin said in a statement.
Oreshkin said recent US trade restrictions have cost Moscow $537.6m.
"Raising our import duties will compensate for only part of this loss," he said.
He added that Russia has "the right" to do this according to the World Trade Organisation (WTO) rules. He said Moscow could introduce further measures in due course.
Last month Russia challenged the US at the WTO, accusing Washington of multiple violations of international trade rules.
It formally asked the United States for "consultations" over tariffs of 25% on steel and 10% on aluminium.
Russia thus joined other powerful WTO members - including the European Union, China, India, Mexico and Canada - in fighting back against President Donald Trump's controversial trade policies.
Under WTO rules, if 60 days pass without consultations resolving the dispute, Russia can ask the WTO to set up a dispute panel. That triggers a long and costly legal battle that could take years to resolve.
Earlier, the Kremlin warned that a trade war between the US and China will have consequences for the world economy.
"Russia will take the necessary measures to protect its interests," Kremlin spokesman Dmitry Peskov told reporters.