Trump will first meet Mr. Moon, then have lunch with Mr. Moon and Japanese Prime Minister Shinzo Abe, then meet separately with Mr. Abe.

U.S. President Donald Trump and South Korean President Moon Jae-in will hold talks on North Korea's nuclear crisis on Thursday amid tensions over whether Trump's harsh rhetoric against North Korean leader Kim Jong Un could lead to a miscalculation.

U.S. officials scrambled to stress diplomatic options remained open after Mr. Trump used his U.N. General Assembly speech on Tuesday to threaten to “totally destroy” nuclear-armed North Korea and blast Kim as a “rocket man” on a suicide mission.

Mr. Trump and Mr. Moon are to sit down at midday on the last day of Trump's four-day visit to New York, where he met with a flurry of foreign leaders gathered for the annual U.N. event.

Mr. Trump will first meet Mr. Moon, then have lunch with Mr. Moon and Japanese Prime Minister Shinzo Abe, then meet separately with Mr. Abe.

Publicly, the South Korean government described Mr. Trump's speech as an expression of how serious the United States views the North Korean nuclear challenge.

“We view the speech as portraying a firm and specific stance on the key issues regarding keeping peace and safety that the international community and the United Nations are faced with,” Mr. Moon's office said in a statement on Wednesday.

But two senior South Korean diplomats, interviewed by Reuters, expressed concern that Mr. Trump's rhetoric could provoke a miscalculation from Kim and prompt him to launch an attack.

The diplomats also said the two governments are not communicating the same message, with South Korea saying it cannot afford another war on the Korean peninsula.

Any allies cant be on the exact same page on every matter but its concerning that we are giving the impression that the two countries have different voices,” one diplomat said.

A senior U.S. official dismissed the South Korean diplomats' worries about a miscalculation and said a cautious approach by past U.S. administrations had not stopped North Korea from developing nuclear weapons and ballistic missiles.

“They're always worried about that,” the official said. “The cautious, go-slow approach of strategic patience has gotten us to where we are.”

U.S. Secretary of State Rex Tillerson told reporters on Wednesday night that U.S.-led sanctions against North Korea are starting to take effect with the North experiencing fuel shortages.

Mr. Trump and Mr. Moon are also at odds over trade. Mr. Trump has complained about the U.S. trade deficit with South Korea, but has so far been persuaded by his top advisers not to terminate a U.S.-South Korean trade agreement as he has threatened.

Mr. Moon, speaking at a business event in New York, urged greater U.S. investment in South Korea and defended the U.S.-South Korea trade agreement known as KORUS.

“It is a fact that the Korea-U.S. FTA is an agreement that benefits both countries by expanding their trade, enhancing market accessibility and increasing their investment and jobs," Yonhap quoted Moon as saying.

It said he added that the U.S trade deficit with South Korea was limited to products and was shrinking while South Korea continued to post large trade deficits with the United States in the service sector.