US President Donald Trump on Wednesday warned North Korea that the world will not tolerate what he called its "nuclear blackmail," vowing an international campaign of "maximum pressure" on Pyongyang, including by China.

"I made clear that we will not allow this twisted dictatorship to hold the world hostage to nuclear blackmail," Trump said in a televised statement a day after returning from his marathon trip to Asia.

Trump said Chinese leader Xi Jinping had pledged to use Beijing's economic leverage over Pyongyang to achieve denuclearization in the North.

"President Xi recognizes that North Korea is a great threat to China," the US leader said