Foreign Minister Vivian Balakrishnan said Saturday in Beijing after returning from North Korea that "things will start happening within the next 24 hours". Kim arrived on an Air China jet, NPR's Elise Hu reports.
Earlier on Sunday, both Trump and Kim arrived in Singapore for the US-North Korean summit.
The bodyguards were glimpsed flanking Kim's Mercedes-Benz limousine as it traveled to the St. Regis Hotel in Singapore on Sunday. But they hope the USA won't ignore North Korea's advanced chemical and biological weapons program, as well as more conventional artillery which remains a threat to the region.
According to Wall Street Journal's Jonathan Cheng, North Korea's main newspaper also covered the leader's trip to Singapore with a front-page photo of Kim boarding the plane.
This has included backing away from an original demand for North Korea's swift denuclearisation.
He added in addition to using bulletproof vehicles, North Korea's security detail would likely deploy layers of protection surrounding the summit venue and try to divert attention from Kim Jong Un's auto whenever he moves.
But the president insisted the U.S. was leaving no stone unturned in its preparations, while warning that patience was needed.
Trump requested Saudi oil support before Iran nuclear decision
Washington was anxious that the sanctions would curb deliveries from Iran and push oil prices up, the sources said. The increase shows that lack of supply that is coming from OPEC crude relative to supply from USA production.
President Trump arrived in Singapore Sunday night ahead of the summit.
Kim's meeting with Singapore Prime Minister Lee Hsien Loong was also covered in the seven-minute news bulletin.
But after a cooling of the rhetoric, both sides began forging tentative contacts that eventually saw Mike Pompeo - the former head of the Central Intelligence Agency who is now secretary of state - meet Kim in Pyongyang.
Both North Korea and the United States have expressed expectations for the outcomes of their first summit meeting set to open in Singapore on Tuesday.
Kim's explosive personality is particularly relevant because going into the North Korea summit, President Donald Trump has suggested that the meeting will be less about preparation and more about attitude.
But then again, nothing about this summit is routine.
With few sources of information other than the state-run media, gossip and word of mouth, most North Koreans are still largely in the dark about the momentous - and potentially life-changing - events that are about to take place outside of their isolated nation.
Another possibility from the summit is a deal to end the Korean War, which North Korea has long demanded, presumably, in part, to get USA troops off the Korean Peninsula and, eventually, pave the way for a North Korean-led unified Korea.
Some critics have said the summit is being rushed through, with Trump keen to chalk up his first major foreign policy achievement.
Any nuclear deal will hinge on North Korea's willingness to allow unfettered outside inspections of the country's warheads and radioactive materials, much of which is likely kept in a vast complex of underground facilities.