Former U.S. National Security Adviser John Bolton suggested Wednesday that President Donald Trump's hardline stance on China may be a facade to boost his dimming re-election prospects and that he may seek to meet North Korean leader Kim Jong Un again to revive his political fortunes.

Bolton, in an interview with Kyodo News, also warned that the 74-year-old president may consider withdrawing U.S. troops from Japan in the "worst-case scenario" if upcoming negotiations over the cost of stationing the American military in the country fail to make headway.

The interview was conducted via video link following the release of Bolton's memoir detailing his time in the White House before he was ousted last September over disagreements on policy issues including North Korea.

Former U.S. National Security Adviser John Bolton speaks during an online interview with Kyodo News on July 29, 2020. (Kyodo)

"Many of Trump's decisions on national security issues were made not based on the merits of the arguments for or against the decision, but on U.S. domestic political considerations, because he needed to maintain support of the Republican Party, of his base, to get re-elected (in November)," he said.

Bolton said the ongoing showdown between the United States and China, most recently over a Chinese consulate in Houston, which Washington has accused of being an espionage hub, "looks" like a hardline policy on Beijing.

This may appeal to U.S. voters since, according to Bolton, more people are concerned about China than before in the wake of the coronavirus, which was first detected in the Asian country.

Trump was initially happy with a hard-fought partial trade deal he signed with China this January, under which the world's second-largest economy agreed to increase its purchases of U.S. goods and services over the next two years by at least $200 billion.

But he began to step up his harsh rhetoric against China after facing domestic criticism over his own handling of the coronavirus, blaming Beijing for failing to stop the spread at its source.

Combined file photo shows U.S. President Donald Trump (L) and Chinese President Xi Jinping. (Kyodo)

Bolton said the question is whether such a tough stance will "last after the election."

While Trump has threatened that it is "always possible" to shut more Chinese diplomatic missions in the United States, Bolton doubted there will be a next move after China retaliated by demanding the United States close its consulate general in the Chinese city of Chengdu.

"I don't think Trump wants to escalate this. I think the line he is trying to walk is to be hardline on China before the election...but not foreclose the ability to get back into a big trade deal negotiation with (Chinese President) Xi Jinping after the election," he said.

Bolton, meanwhile, said Trump may also turn to the North Korean leader to revive his political fortunes, even though talks on ridding Pyongyang of its nuclear weapons have stalled for months over the degree of sanctions relief the United States will offer to Pyongyang in return for its denuclearization steps.

"If Trump still looks to be in trouble politically in October -- we have something in this country called 'the October surprise,' what somebody does when they're in trouble politically with a month to go before the election -- and what I've suggested may be Trump's October surprise is a fourth summit with Kim Jong Un," Bolton said.

North Korean leader Kim Jong Un and U.S. President Donald Trump at the demilitarized zone (DMZ) separating the South and North Korea on June 30, 2019. (KCNA/Kyodo)

The outcome of such a meeting could be declaring a formal end to the 1950-1953 Korean War for the two Koreas and a reaffirmed commitment to the denuclearization of the Korean Peninsula, he said.

"In other words, not much of substance, but enough so that Trump could declare a victory and say 'I had my fourth meeting with Kim Jong Un. We've got this significant new agreement, so that's why I should be re-elected on Nov. 3,'" Bolton said.

On the so-called host-nation support issue, Bolton said Trump's demand that Japan pay $8 billion annually, a figure he disclosed in his memoir, is the president's "opening bargaining position."

Japan's financial support totals nearly 200 billion yen ($1.9 billion) annually, covering costs for base workers, utilities and other items.

Japan and the United States are expected to start negotiations on host-nation support later this year, given that the current five-year payment agreement is set to expire at the end of next March.

Asked if Trump will pull U.S. forces out if the negotiations do not turn out well for him, Bolton said, "Well, I think that's the worst-case scenario."

"But, unlike other U.S. presidents that wouldn't even think about it, I think he would think about it," he said.