Before leaving Tokyo, Japanese Prime Minister Shinzo Abe emphasized that during his lightning visit to Washington, he hoped to "closely coordinate and agree" with Trump on an approach to the North Korea issue.
With less than a week to go before meeting North Korean leader Kim Jong Un, US President Donald Trump plays host Thursday to Japanese Prime Minister Shinzo Abe, who wants his voice heard ahead of the unprecedented talks.
Trump and Abe will hold a joint press conference at the White House in the early afternoon, before heading to Canada for what promises to be a tense Group of Seven summit clouded by the US leader's aggressive trade policies.
Since the first inkling that a Trump-Kim summit could be on the cards, Japan has repeatedly insisted that Washington be mindful not to let its guard down with the nuclear-armed regime in Pyongyang.
And by coming to Washington to see Trump for the second time in less than two months, Abe wants to be sure to get his point across to the US president, amid the intense diplomatic flurry over the future of the Korean peninsula.
Before leaving Tokyo, the Japanese leader emphasized that during his lightning visit to Washington, he hoped to "closely coordinate and agree" with Trump on an approach to the North Korea issue.
And he clearly outlined what would need to happen for the June 12 summit in Singapore to be a success: tangible progress on curbing the North's nuclear and ballistic missiles programs, as well as answers about Japanese nationals kidnapped by Pyongyang in the 1970s and 1980s.
At their last meeting at Trump's Florida retreat in April, the US president promised Abe to raise the politically sensitive abductions issue in any talks with Pyongyang.
But the subject is hardly a priority for the businessman-turned-president, whose strategy appears to be in constant flux.
Above all, Trump seems most enthused by the notion of being the first sitting US leader to hold direct talks with a scion of the ruling Kim dynasty.
The intensifying diplomacy on North Korea has so far left Abe as the odd man out: Trump is preparing to meet Kim, while Chinese President Xi Jinping and South Korea's Moon Jae-in have each already seen the North's leader twice.
Japan left 'isolated' after Singapore?
For Richard Armitage, a former senior diplomat during the administration of George W Bush, Tokyo runs a very real risk of finding itself out in the cold after the Trump-Kim talks.
"We should absolutely prevent decoupling -- decoupling Japanese and US security," he told AFP.
"This is and has been an aim of China and North Korea for a long time, and we can't allow this to happen. That would be falling into a terrible trap."
Trump and Abe so far seem to have forged a sort of friendship, but even that bonhomie was revealed to be limited at their last meeting.
On Thursday, it could again be put to the test -- beyond North Korea, they are also meant to discuss the thorny issue of tariffs, which Washington says were put in place to protect American workers.
"I will stress that measures to restrict trade would not serve the interests of any country," Abe said before heading to Washington.
Japan had hoped to convince the US to shield it from fresh tariffs on steel and aluminium imports, and did not hide its bitter disappointment when those talks failed.
The government in Tokyo warned of the "grave impact" that US tariffs could have on bilateral ties and the world trading system.
"The US government's trade measures, citing its security, makes us concerned that they could disrupt the global market," government spokesman Yoshihide Suga told reporters on Monday.