US Secetary of State Rex Tillerson calls for cooperation with China in first visit to country

US Secretary of State Rex Tillerson has used his first official visit to China to call for a "constructive and results-oriented relationship" between the two countries.

Tillerson said China and the US were committing to persuading the North Korean government "to choose a better path and a different future for its people". But Chinese Foreign Minister Wang Yi urged the US to be "cool-headed" in pursuit of its goals.

On Friday, Tillerson said "all options are on the table" regarding North Korea, refusing to rule out the possibility of military action against the secretive nation. Today, his rhetoric mellowed only slightly as he claimed "things have reached a rather dangerous level" on the Korean peninsula.

Despite both China and the US aiming to encourage North Korea to become a nuclear weapon-free state, the country's government continues to defy UN rules and test missiles capable of carrying nuclear warheads – firing four in the last week.

While the US is not currently threatened directly, some observers believe it could be within a few years. Key allies South Korea and Japan are already within range of North Korean missiles and have been subject to threats.

Tillerson maintained the US and China were "committed" to doing anything they could to "prevent any type of conflict from breaking out" but did not say what actions would be 'red lines' for the US. He also refused to answer a question on whether a tweet sent by President Trump about China's inaction on North Korea had made diplomacy more difficult.

Yi said there was a "fundamental consensus" regarding the nuclear issue in North Korea. However, he lamented the breakdown of the Six Party talks – discussions held between regional powers – which meant dialogue with North Korea was no longer possible.

The Chinese minister also struck a markedly more moderate tone than Tillerson.

"We hope all parties, including our friends from the United States, could size up the situation in a cool-headed and comprehensive fashion and arrive at a wise decision," Yi said. "We stand ready to continue to maintain close communication and the necessary coordination with the US side on this issue."

China has long been tacitly supportive of North Korea but has recently become more agitated with the state's increasing aggression and unpredictability. After a North Korean missile test in February, China banned coal imports from the country. The fuel accounts for up to 40% of all North Korean exports, according to the New York Times.

But China is also fearful of the effects of an outright conflict on its border could bring, such as large numbers of refugees and the possibility of the entire peninsula eventually aligned with the West.

Chinese President Xi Jingping is expected to travel to America next month. The world's two biggest economies, the US and China have had an uneasy relationship since Donald Trump became President. During his campaign, Trump frequently accused China of being a "currency manipulator" and of stealing American jobs.

Soon after his election, Trump spoke with the President of Taiwan, Tsai Ing-wen, greatly angering China, who saw it as a violation of the 'One China' policy the US has pursued for decades.

More recently, China has been aggravated by a Thaad missile defence system being installed in Souty Korea, which it says allows the US to view its radar systems.