Who has now pledged his "forever and forever support" to Mr Trump in a letter. Here's a bit more about the ex-basketball star who's friends with both Mr Trump and Kim.

The US leader's motorcade is driving to the Metropole Hotel, the same venue where he dined with Mr Kim last night.

Image source, Reuters

Hanoi is at a standstill as the leaders converge on the Metropole hotel.

Vietnamese police are standing guard as cars slowly making their way to the summit venue:

Image source, AFP

Journalists in the massive media centre are gathering around screens watching live footage of the leaders arrive at the summit venue.

As with the past two days, the leaders' routes around the city have been lined with people. Some clearly fans - of the leaders or of peace - while others just appeared to be curious about the big event taking over their city.

President Trump has left his hotel and is driving across town - on closed streets - to meeting Kim Jong-un. We're expecting that meeting in about 20 minutes.

While the leaders have been moving around the Vietnamese authorities have been putting up rolling road blocks, causing traffic chaos in this busy city but also briefly some glorious views of empty roads. Here's the scene outside just now.

That's how Mr Trump has described the summit that's happening now in Vietnam. Here's a full breakdown of what him and Mr Kim talked about last night over their first face-to-face chat in Hanoi. , external

The big topic is North Korea's nuclear weapons which most of the world does not want it to have. It is under crippling economic sanctions which it wants relieved.

In Singapore, Kim Jong-un vaguely promised to "denuclearise" - but it's never been established quite what that means, nor how the progress will happen. It was some reciprocal action from the US. It remains unclear whether the two men have yet reached a deal in their second meeting which will deliver concrete development, or whether they've just got a photo op and promises to keep talking.

You might be thinking we’ve seen this before - and we sort of have. In June 2018 Mr Trump and Mr Kim had what was repeatedly called a landmark summit in Singapore.

It WAS historic - as no sitting US president had ever met a North Korean leader. That’s because for decades, the US policy was that North Korea should not get the biggest badge of diplomatic recognition in the world - a handshake with the US president - until it made significant progress towards giving up its nuclear weapons and addressing its dreadful record on human rights.

Image source, Getty Images

Donald Trump and Kim Jong-un want very different things out of this summit - we'll let the BBC's Seoul correspondent Laura Bicker explain more.

Vietnam’s seen as a good location for several reasons. It has diplomatic relations with both the US and North Korea, despite once having been enemies with the US - and so could be used as an example of two countries working together and setting aside their past grievances.

Ideologically, both Vietnam and North Korea are communist countries, though Vietnam has since become one of the fastest growing economies in Asia. Here are some other things Mr Kim might learn from Vietnam.

Image source, Reuters

Here's the BBC's Laura Bicker with a quick explanation from Hanoi.

This from James Pearson, Reuters correspondent in Hanoi.

Last night Mr Trump tweeted this striking video recapping Wednesday's events, complete with soaring, optimistic soundtrack. Check out the handshake at 21 seconds...

If you want a primer on what's going on today in Hanoi, here's our need-to-know guide - including why this is happening again so soon after their historic meeting in Singapore.

Over a dinner said to include US sirloin steak and pear kimchi, Mr Trump and Mr Kim - formerly arch enemies - shared warm words. Mr Trump hailed Mr Kim as a "great leader" and was flattered as "courageous" in return.

We're expecting Mr Trump and Mr Kim to be on the move in an hour or so. Last night they had a very cordial reunion after their first historic meeting in Singapore last year, then a cosy dinner. Mr Trump said both were "great".

Here's our full story on the events so far.

Image source, Reuters

Hello, and welcome to the BBC’s live coverage of the second summit between US President Donald Trump and North Korea’s Kim Jong-un. All the action is happening in Hanoi, Vietnam’s capital. We’re bringing you coverage from the heart of the summit, from our correspondents and experts around Hanoi and the region, and from interested parties around the world.