US President Donald Trump says Washington has a "great relationship with China." He made the remarks in a speech at an Iowa community college, standing beside former Iowa Governor Terry Branstad – the new US ambassador to Beijing. 

Trump tweeted: "While I greatly appreciate the efforts of President Xi in China to help with North Korea, it has not worked out. At least I know China tried!” 

His comments came just a day after he said Chinese efforts in containing DPRK's nuclear programs had failed.

China says it has made "unremitting" efforts to resolve the nuclear issue and ease tensions on the Korean Peninsula after Trump tweeted that Beijing had not succeeded in helping.

Chinese Foreign Ministry spokesperson Geng Shuang said that China has been making unremitting efforts to resolve the nuclear issue on the Korean Peninsula, adding that the country has been playing a constructive role.

“Generally speaking, our contributions have been recognized by all, and our efforts have been indispensable. Given the recent escalation of tensions on the Peninsula, China has stepped up its efforts to promote peace talks and bring the issue back to the track of dialogue and consultation. The crux of the nuclear issue does not lie with China," Geng explained saying collective wisdom and joint efforts are needed to resolve the issue.