The United States intends to pressure China for further action to stop North Koreas' nuclear programme, US Ambassador to the United Nations, Nikki Haley said on Sunday. "The only country that can stop North Korea is China, and the Chinese are aware of this and they have to move, and we will continue to pressure China to do so," Haley said in an interview with ABC News on Sunday, days before Chinese President Xi Jinping's upcoming visit to Washington. The Chinese president will pay a visit to the United States on Thursday and Friday, where he will hold a meeting with his US counterpart Donald Trump at the latter's headquarters in Mar A Lago, Florida. Trump tweeted Thursday that the meeting with his Chinese counterpart would be "very difficult," especially because of trade differences between the two powers. However, Haley asserted that "the most important conversation will be on how to manage the proliferation of nuclear weapons in North Korea". Beijing has announced a suspension of its coal exports to North Korea in response to UN sanctions to persuade the country to abandon its nuclear and ballistic programs. But Haley considered the move insufficient, adding: "We know that coal enters North Korea through other means, we want to see effective moves by China to condemn North Korea and not just words." North Korea has sought to develop a nuclear program for years. In 2006, despite sanctions and economic difficulties, North Korea began testing its first nuclear weapon. It has since carried out more successful tests in 2009 and 2013.