A consequential round of trade talks between the United States and China began with smiles and a dinner in Washington.

Yet the outward optimism did not appear to translate into a last-minute agreement that could stave off a planned increase in tariffs on $200 billion worth of Chinese goods.

Without a deal, the tariff hike — which President Donald Trump previewed earlier in the day — will take effect at midnight.

The President signaled no qualms at the move, which has worried businesses and investors.

Instead, Trump says he is willing to go even further, threatening to slap tariffs on nearly all Chinese imports.

Hours before US and Chinese officials sat down at the offices of the US trade representative, Trump revealed from the White House that he had just received an upbeat letter from his Chinese counterpart, Xi Jinping, and suggested a deal was still attainable.

But he reiterated his belief that tariffs will benefit the United States, and appeared unfazed by market losses prompted by the renewed trade war.

Even a week ago, top administration officials appeared bullish on the chances a deal would soon be struck with China.