US President Donald Trump has instructed officials to consider a further $100bn (£71.3bn) of tariffs against China, in an escalation of a tense trade stand-off.
These would be in addition to the $50bn worth of US tariffs already proposed on hundreds of Chinese imports.
The proposal comes after China retaliated to that by threatening tariffs on 106 key US products.
The tit-for-tat moves have unsettled global markets in recent weeks.
Analysts have said a full blown trade war between the US and China would not be good for the global economy or markets - and that ongoing behind-the-scenes negotiations between the two giants are crucial.
However, market reaction in early Asia trade on Friday suggested investors were not as troubled, and that trade war fears were somewhat exaggerated.
In China, Hong Kong's Hang Seng was in positive territory, up 1.5%. Japan's benchmark Nikkei 225 was trading higher after the morning session.
Last week Washington set out about 1,300 Chinese products it intended to hit with tariffs set at 25%. That followed an announcement earlier this year that the US would impose import taxes on aluminium and steel, which would include China.
The White House said its latest tariffs were a response to unfair Chinese intellectual property practices, such as those that pressure US companies to share technology with Chinese firms.
China responded swiftly and robustly by proposing tariffs on 106 key US products, including soybeans, aircraft parts and orange juice, narrowly aimed at politically important sectors in the US, such as agriculture.
But in a statement on Thursday Mr Trump branded Beijing's retaliation as "unfair".
"Rather than remedy its misconduct, China has chosen to harm our farmers and manufacturers
"In light of China's unfair retaliation, I have instructed the USTR (United States Trade Representative) to consider whether $100bn of additional tariffs would be appropriate under section 301 and, if so, to identify the products upon which to impose such tariffs," Mr Trump said.
He said he had also instructed agricultural officials to implement a plan to protect US farmers and agricultural interests.
Meanwhile, China has initiated a complaint with the World Trade Organisation over the US tariffs, in what analysts say could be a sign that this will be a protracted process.
The WTO circulated the request for consultation to members on Thursday, launching a discussion period before the complaint heads to formal dispute settlement process.