WASHINGTON (AFP) - While slapping duties on steel and aluminium imports, President Donald Trump struck a more conciliatory tone towards China, pointing to negotiations under way to trim Washington's soaring bilateral trade deficit with Beijing.

"We're negotiating now with China. We're in the midst of a big negotiation. I don't know that anything is going to come of it," Trump said at the White House on Thursday (March 8) while rolling out the new trade barriers.

"They have been very helpful. President Xi, I have great respect for, lot of respect," Trump added. "We're going to cut down the deficits one way or another."

Trump claimed the US had a trade gap with China of "at least US$500 billion (S$657.6 billion)" and said that, counting losses on intellectual property, "it's much bigger than that."

According to Commerce Department data, in 2017 the US-China trade deficit in goods only was actually US$375.2 billion, the highest on record. US goods exports to China were also at a record high of US$130.4 billion.

Trump also cited the founder of electric car maker Tesla, Elon Musk, saying US cars exported to China were met with duties of 25 per cent while Chinese cars imported to the United States were taxed at a rate of only 2.5 per cent.

"It's got to change," said Trump.

Trump in recent days has referred to negotiations underway with Beijing to reduce the US bilateral trade deficit by US$100 billion without specifying how this can be done.

Washington has also launched a process which could see the US take retaliatory trade measures over intellectual property. At the same time, the United States and China maintain delicate diplomatic relations over efforts to contain North Korea's nuclear weapons programme.