Trump: China’s pressure on North Korea hasn’t worked

President Donald Trump says that he appreciates China’s efforts to exert pressure on North Korea, but “it has not worked out.”

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

While I greatly appreciate the efforts of President Xi & China to help with North Korea, it has not worked out. At least I know China tried!

— Donald J. Trump (@realDonaldTrump) June 20, 2017

His tweet comes a day after learning that Otto Warmbier, an American student who was returned from North Korea to the U.S. in a coma last week, had died.

Trump said Tuesday that it was a “total disgrace” what happened to Warmbier, but doctors and the administration haven’t offered an explanation for the student’s condition preceding his death.

READ MORE: Trump offers condolences to family whose son died after North Korean detainment

Trump has called repeatedly on China to help exert pressure on North Korea, particularly with regard to its nuclear ambitions.

The Trump administration is considering banning travel by U.S. citizens to North Korea, officials said Tuesday, as outrage grew over the death Otto Warmbier and President Donald Trump declared it a “total disgrace.”

Secretary of State Rex Tillerson, who has the authority to cut off travel to North Korea with the stroke of the pen, has been weighing such a move since late April, when American teacher Tony Kim was detained in Pyongyang, a senior State Department official said. No ban is imminent, but deliberations gained new urgency after Warmbier’s death, said the official, who requested anonymity to discuss internal diplomatic discussions.

WATCH: Parents of U.S. student freed from North Korea speak out