Trump's marathon Asia tour will be dominated by concerns in the region and beyond that tit-for-tat insults between the US and nuclear-armed North Korea could spiral into a devastating war.
His first stops are Japan and South Korea -- frontline US allies in the effort to force Pyongyang to abandon its nuclear programme, and the two countries with most to fear should a full-scale conflict break out.
Trump and his "friend" Shinzo Abe, Japan's prime minister, enjoy a close personal relationship and the three-day Japan trip is noticeably relaxed, with the two leaders teeing off for a round of golf before being serenaded by wacky internet sensation Pikotaro.
The Japanese leader has emerged strengthened from a crushing victory in a snap election and has firmly supported Trump in his policy of exerting maximum pressure on Kim, backed up with the threat of military force.
Japan has seen missiles fired over its northern island amid threats by Pyongyang to "sink" it into the sea.
"Trump only has to play golf in Japan, as he knows Japan will follow (the US) whatever happens. Everything has been sorted out beforehand," Tetsuro Kato, political scientist at Tokyo's Hitotsubashi University, told AFP.
Before the trip, Trump warned China that Japan could take matters into its own hands.
"Japan is a warrior nation, and I tell China and I tell everyone else that listens, I mean, you're gonna have yourself a big problem with Japan pretty soon if you allow this to continue with North Korea," Trump said on Fox News.
'Appeasement'
While Trump has been in regular contact with the hawkish Abe during the North Korean missile crisis, he pointedly failed to speak to South Korean President Moon Jae-in for several days after Pyongyang's second intercontinental ballistic missile test in July.
Analysts point to Abe and Moon's contrasting approaches to the crisis as an underlying factor, although both leaders will be hoping to press Trump into reaffirming Washington's steadfast commitment to their defence.
Abe has backed his line that "all options," including military action, are on the table, while the more dovish Moon favours engagement with the North to bring it to the negotiating table.
Trump labelled Moon's approach as "appeasement" on Twitter, a comment that did not go down well in the Blue House.
"The two sides have subtle differences in their positions," said Kim Hyun-Wook, a professor at the Korea National Diplomatic Academy.
The allies have underlying suspicions about each other, he added: Washington worries about the South's liberal government holding secret talks with the North, while Seoul is concerned about a unilateral US military strike on Pyongyang.
Some have pointed to Trump's one-night stay in South Korea -- compared to longer visits to Japan and China -- as a sign that Seoul is being sidelined.
But Moon's office was quick to dismiss the claims, noting that Trump will address the South Korean parliament.
However, he will not follow the well-trodden path to the De-Militarized Zone dividing the Korean peninsula -- a visit derided in Washington as a bit of a "cliche."
Donald Trump walks towards the motorcade with first lady Melania Trump to meet servicemen in Honolulu. Source: The Star-Advertiser
'Massive military response'
The groundwork for Trump's trip was laid by Defence Secretary Jim Mattis, who warned North Korea of a "massive military response, effective and overwhelming," if Pyongyang resorted to using nuclear weapons.
Mattis stressed that diplomacy was Washington's "preferred course of action," adding, "our diplomats are most effective when backed by credible military force," as three US aircraft carriers are currently operating in the region.
On Friday, US supersonic B-1B Lancer bombers overflew the Korean peninsula, as Seoul's spy agency reportedly warned the North might be readying another missile test.
From Seoul, Trump travels to China to meet his counterpart Xi Jinping who, like Abe, has solidified his grip on power after being handed a second term.
He then travels to an APEC summit in Vietnam before heading to an ASEAN gathering of Southeast Asian leaders.
Some observers were fretting that a gaffe by the famously ad-lib president could send tensions rising on the peninsula.
"It will be a disaster if he speaks off the cuff and without thinking," said professor Koo Kab-Woo from the University of North Korean Studies in Seoul.
"If Trump says anything that can provoke North Korea, it could send military tensions soaring again."
