Beijing: Secretary of State Rex Tillerson signalled the Trump administration was prepared to scrap nearly a decade of US policy toward North Korea in favour of a more aggressive effort to eliminate the country's nuclear weapons program.

Whether that means pre-emptive action, which he warned was "on the table," will depend a great deal on how China responds.

A security official stands guard under red flags at Tiananmen Gate in Beijing, China. Credit:Bloomberg

North Korea relies on Chinese trade and aid to keep its economy afloat, and China has long been unwilling to withdraw that support. Up to 40 per cent of its foreign currency -- essential for buying goods abroad -- comes from a network of about 600 Chinese companies, according to a recent study by Sayari Analytics, a Washington financial intelligence firm.

Tillerson, who is travelling to China, a day after saying in Seoul, South Korea, that the United States would not negotiate with North Korea on freezing its nuclear and missile programs. His interactions with his hosts in Beijing, and whether he takes a hard line with China over its support for North Korea, will be closely watched -- as will be China's response.