WASHINGTON, United States (AFP) — Since returning to the White House, President Donald Trump has boasted of ending either six or seven wars — a matter of much dispute — and has been pushing with mixed success to bring peace to Ukraine.

One hotspot not yet on his second-term radar has been North Korea, despite Trump's unusually personal diplomacy during his first term when he met leader Kim Jong Un.

Trump could find a chance to pivot on Monday as he welcomes to the White House South Korea's new President Lee Jae Myung, an advocate of outreach with the North.

Trump, who did not secure a deal on Ukraine during a 15 August summit in Alaska with Russian President Vladimir Putin, has an "appetite for big news," said Victor Cha, a top advisor on Asia to former president George W. Bush.

"Having the Alaska summit not go as well as he wanted may make the president much more interested in seeing this meeting with South Korea come off very well," said Cha, Korea chair at the Center for Strategic and International Studies.

Trump had expressed striking fondness for Kim after their three meetings, once offering that he and the young totalitarian "fell in love."

But Trump could find a new Kim this time, one emboldened since their diplomatic love affair.

North Korea, one of the most sanctioned and isolated countries, has cashed in with Russia by supplying more than 10,000 troops plus weapons to Moscow's offensive in Ukraine, according to Western and South Korean intelligence.

"If there is one reason why North Korea's not interested in any of these dialogues with the South Koreans and the Americans, it's because of all they're getting from Russia," Cha said.

Former US president Joe Biden also offered dialogue with North Korea, albeit among lower-ranking officials, but Pyongyang rebuffed him.