Washington (United States) (AFP) – US President Donald Trump said Wednesday he would meet North Korean leader Kim Jong Un later this year, in what would be their first encounter of Trump's second term.

Trump also said that North Korea had 57 "very powerful" nuclear weapons, in a rare and unusually specific assessment by a US president of Kim's atomic arsenal.

"Yeah, I will be," Trump told reporters during a tour of a new helipad he is building at the White House, when asked if he planned to meet Kim later in 2026.

Trump gave no details, but the Wall Street Journal reported that he was eying a meeting when he travels to China for an Asia-Pacific Economic Cooperation (APEC) summit in November.

Trump defended planning to meet Kim at the same time as the US president wages a war with Iran that he has justified on the grounds of preventing Tehran from getting the bomb.

"He has 57 very powerful nuclear weapons. Should have never allowed it to happen... If I were president, I wouldn't have allowed it," Trump said, referring to the North Korean leader.

"But he's got them. I get along with him very well. I can't let Iran have a nuclear weapon. And I know Kim Jong Un very well, and he's going to be fine."

Trump's announcement comes two days after he ordered the United States to scale back "inappropriate and hostile" military drills with South Korea.

The US leader cited his "good relationship" with Kim in the decision.

Trump and Kim met three times in his first spell in the White House, and at the time he said they "fell in love" after exchanging "beautiful letters." But they haven't met in his second term.

In recent days Trump has dropped growing hints about communications with Kim, although he wouldn't confirm on Wednesday that the pair were exchanging letters.

The powerful sister of Kim Jong Un said Wednesday she was "unaware" of reported communication between her brother and Donald Trump, but said ties between the two remained "excellent."