Donald Trump slams China as currency, trade manipulator, enters South China Sea debate

Trump's approach to China
Trump's approach to China

Donald Trump has lashed out again at China, accusing Beijing of manipulating its currency, unfairly taxing U.S. products and militarizing the South China Sea.

Tweeting on Sunday evening, the U.S. president-elect said:

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 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!

This followed a tweet-heavy weekend, in which Trump used the social media platform to threaten a 35 percent tax on products sold in the U.S. by any domestic business that moved operations overseas. The real estate mogul had campaigned on a platform of boosting business and American jobs.

The tweets also came as Trump strained relations with China on Friday by accepting a congratulatory phone call from Taiwan's President Tsai Ing-wen, breaking almost four decades of U.S. foreign policy that has acknowledged Taiwan is part of China.

China considers Taiwan a renegade state that can be retaken by force at any time and Beijing has made clear its dislike of pro-independence Tsai. At the weekend, China lodged a diplomatic protest with the U.S. over the call - it wasn't clear if the protest was made directly to Trump's transition team - but blamed Taiwan for the "petty action."

The reference to the South China Sea is particularly sensitive, as the U.S. and China are locked in a battle of wills over the maritime region, which China, as well as other Asian countries, claims as its own.

In July, the Permanent Court of Arbitration in The Hague found that China's claims of historical rights to the region - which is a key international shipping route - were not founded on evidence and were counter to international law. The court found that Chinese efforts to create man-made islands on top of atolls and reefs, as well as its large-scale fishing in the disputed areas, were illegal.

China has refused to recognize the court's authority. Meanwhile, the U.S. had continued to assert its right to conduct naval patrols in the area.

Follow CNBC International on Twitter and Facebook.