The diplomat, who accompanied Foreign Minister Wang Yi during talks in Washington last week, said the two countries had agreed on the need for harsh sanctions against North Korea for defying UN resolutions.
However, the diplomat, speaking on condition of anonymity because of the sensitivity of the issue, said the US should also provide incentives to North Korea to return to negotiations, such as offering progress on a permanent peace agreement between the sides. The two countries are still technically at war because the 1950-53 Korean War ended with a cease-fire, not a peace treaty.
The US and South Korea also bear responsibility to avoid actions that North Korea might view as provocative, such as scheduled military drills, he said. "We hope that after the adoption of the resolution all sides should refrain from taking any measures that could escalate."
China is North Korea's most important ally, biggest trading partner and key source of food and fuel. However, Beijing says its influence with Kim Jong Un's government is limited and has argued against measures from the international community that could spark its collapse, potentially leading to a wave of refugees crossing the border into China and the stationing of US and South Korean troops in the North.
The proposed sanctions would also limit and in some cases ban exports of coal, iron, gold, titanium and rare earth minerals from North Korea and would prohibit countries from supplying aviation fuel, including rocket fuel, to the country. Items such as luxury watches, snowmobiles, recreational water vehicles and lead crystal were also added to a long list of luxury goods that North Korea is not allowed to import.