US President-elect Donald Trump on 5 December accused China of currency manipulation and military expansionism in the South China Sea, days after offending Beijing by speaking over the phone with Taiwan President Tsai Ing-wen.
The two tweets from Trump are expected to add to the US-China tension.
"Did China ask us if it was OK to devalue their currency (making it hard for our companies to compete), heavily tax our products going into their country (the US doesn't tax them) or to build a massive military complex in the middle of the South China Sea?" Trump said in a series of tweets.
"I don't think so!" Trump said in his second tweet.
Did China ask us if it was OK to devalue their currency (making it hard for our companies to compete), heavily tax our products going into..— Donald J. Trump (@realDonaldTrump) December 4, 2016
their country (the U.S. doesn't tax them) or to build a massive military complex in the middle of the South China Sea? I don't think so!— Donald J. Trump (@realDonaldTrump) December 4, 2016
The president-elect has already infuriated China by talking over the phone with the Taiwanese President, the first by a top American leader since 1979.
The Washington Post said Trump's protocol-breaking telephone call with Taiwan's leader was an intentionally provocative move that establishes the incoming president as a break with the past.
China was a frequent target of Trump's during his presidential campaign and, as he prepares to take office next month, every sign points to his taking an aggressive line with Beijing.
China regards self-governing Taiwan as a breakaway province, and the two sides enjoy a fragile peace marked by delicate political rhetoric and rising economic integration. China lodged a diplomatic protest with the US over the call.
US politicians often accuse China of artificially depressing its currency, the Renminbi, in order to boost its exports. China claims much of the South China Sea. Vietnam, the Philippines, Malaysia, Brunei and Taiwan also have claims.
An international tribunal in the Hague in July deemed the bulk of China's territorial claims in the South China Sea to have no legal basis under the UN Convention on the Law of the Sea.