Singapore: Less than six months ago US President Donald Trump and North Korean leader Kim Jong-un traded insults, flaunted their military might and threatened each other with nuclear annihilation. Now things seems to have changed dramatically with the two leaders ready to meet.

When they finally come face to face at a specially prepared hotel conference room on the island resort of Sentosa here on Tuesday, it will be the first time a North Korean leader has met a sitting US president.

Trump hopes the landmark talks will kick-start a process that eventually see Kim give up his nuclear weapons in an irreversible manner that can be verified internationally. The two leaders have had an extraordinary up-and-down relationship over the past 18 months.

Trump, 71, had called Kim "Little Rocket Man" and threatened to unleash "fire and fury like the world has never seen" on North Korea as it conducted several ballistic missile tests in defiance of international warnings. In return, Kim, said to be in his mid-thirtees, called Trump "mentally deranged" and a "dotard".

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North Korea also threatened to strike Guam, an American territory in the Pacific Ocean. The North Korean leadership, including Vice Minister of Foreign Affairs Choe Son Hui has also taunted Washington, calling Vice President Mike Pence a "political dummy." In March, Trump surprised the world by accepting an invitation from Kim to meet in person.

But last month, Trump abruptly cancelled the Singapore summit, citing the "tremendous anger and open hostility" by Pyongyang. However, he took a U-turn soon and said the White House was proceeding with the preparations for the summit. Ahead of his much-anticipated meeting with Kim, the US President sounded optimistic and said the meeting would be a "one-time shot" at peace.

"I feel that Kim Jong Un wants to do something great for his people," Trump said. "And he has that opportunity, and he won't have that opportunity again." Calling his trip "a mission of peace," he said the meeting as a rare opportunity for Kim and said the US was going in with a positive outlook.

At the same time, Trump said there was a "good chance" the meeting would not work out and claimed he would know almost immediately after the start of talks how the situation would progress. "I think within the first minute I'll know," Trump said.

Trump said at the least, he hoped the meeting would start a dialogue and a direct understanding between himself and the reclusive leader of North Korea. "At a minimum, I do believe, at least we'll have met each other," Trump said, adding later that "hopefully, we will have liked each other." While en route to Singapore, Trump said he looked forward to meeting Kim on what he anticipated would be an exciting day.

"I am on my way to Singapore where we have a chance to achieve a truly wonderful result for North Korea and the World," Trump wrote in a pair of tweets.

"It will certainly be an exciting day and I know that Kim Jong-un will work very hard to do something that has rarely been done before ... Create peace and great prosperity for his land. I look forward to meeting him and have a feeling that this one-time opportunity will not be wasted!" But experts say the negotiating positions of the two sides remain unchanged, and it is unclear whether this unprecedented encounter will yield anything substantive.

They said questions remain over Kim's willingness to fully abandon his nuclear programme, dismantle weapons and allow independent experts in to verify and inspect every site in the country that might be involved. There is also the question of what will become of North Korea's short and medium-range ballistic missiles, which has been a great concern for North Korea's neighbours, including Japan.

Meanwhile, quoting sources, CNN reported that US officials have established a contingency plan for a potential second day of discussions between Trump and Kim depending on the direction of their planned meeting on Tuesday. (PTI)