FIGHTER jets and helicopters were scrambled to investigate a mysterious UFO over Korea's Demilitarised Zone - hours after Donald Trump's historic meeting with Kim Jong-un at the border.

South Korea's military said its radar detected "traces of flight by an unidentified object" heading across the frontier from North Korea early today.

11 US president Donald Trump and North Korean leader Kim Jong-un shake hands at the Demilitarised Zone on Sunday Credit: Reuters

11 The historic moment Mr Trump steps across the border into North Korea - becoming the first US President to set foot in the country Credit: AFP or licensors

11 Mr Trump and Mr Kim suggested they were ready for further nuclear talks after the brief meet Credit: AFP or licensors

It came hours after Mr Trump yesterday became the first US president to set foot in North Korea as he shook hands with tyrant Kim at the world's most heavily fortified border.

The radar sighting sparked a full-scale military response as tensions remain high between the two countries.

The South's Yonhap news agency said the flying object "showed a flight trace that a helicopter could display" and that it flew from north to south across the DMZ's military demarcation line.

News reports said South Korea launched fighter jets and helicopters because it believed it could be a North Korean aircraft flying across the border into South Korea.

The Joint Chiefs of Staff said it could only confirm that it deployed unidentified surveillance assets to find what that object was.

Later a spokesman said commanders now believed it was a flock of birds that sparked the false alarm.

11 Radar spotted a trace of an unknown object flying over the Demilitarised Zone between North and South Korea

'AMAZING EVENT'

The DMZ - 160 miles long and 2.5 miles wide - has separated the two countries since fighting ceased in the 1950-53 Korean War.

It is peppered with an estimated two million mines, lined with razor wire, watchtowers and tank traps, and guarded by battalions of troops on each side.

Artillery shells and rockets have occasionally been fired across the Cold War frontier, which is only 35 miles from Seoul.

Open hostilities have eased since the North entered talks on its nuclear weapons program.

Sunday's historic meeting between Mr Trump and Mr Kim took place at the border village of Panmunjom where the armistice was signed in 1953.

North Korea's state media described their third meeting as "an amazing event".

Kim had accepted Trump's Twitter invitation to “say hello” and “shake hands” in an attempt to revive stalled nuke talks.

He was waiting to greet the US president as he stepped across the low concrete barrier and said he was "proud" he had come.

Mr Trump in return told reporters: "I just want to say this is my honour. Stepping across that line is a great honour, great progress has been made, great friendships have been made and this has been, in particular, a great friendship."

He also invited the North Korean leader to the US for a visit and added "history has been made".

The two men then both stepped back to the southern portion to sit down in the pastel blue Freedom House for what was said to be a brief meeting.

Donald Trump and North Korean leader Kim Jong-un shower praise on each other at a press conference after their meeting at the Korean Demilitarised Zone

'READY FOR NUKE TALKS'

Afterwards Mr Trump said the two nations had agreed to resume talks in the coming weeks.

And today South Korea said it hoped the diplomatic momentum created by the latest Trump-Kim meeting would help revive dialogue with Pyongyang which had stalled amid an impasse over sanctions.

Mr Trump was photographed getting his first glimpse of North Korea as he stood atop Observation Post Ouellette.

In a press conference, Trump spoke about his "chemistry" with the North Korean leader.

"For some reason we have a certain chemistry - or whatever. Let's see what happens,” he said.

“We have a long way to go. But I'm in no rush.

“So, I just want to say that we are going to be heading out to the DMZ and it's something I planned long ago but had the idea yesterday to maybe say hello, just shake hands quickly and say hello.”

He had earlier met the South Korean president Moon Jae-in, having flown to Seoul fresh from meeting other world leaders including China's Xi Jinping at the G20 summit in Osaka.

While still in Japan, Trump had approached Kim via Twitter in an attempt to set up a meeting.

"I will be leaving Japan for South Korea (with President Moon),” Trump tweeted.

“While there, if Chairman Kim of North Korea sees this, I would meet him at the Border/DMZ just to shake his hand and say Hello(?)!"

The president has been trying to restart nuclear talks with the North after they broke down during his second summit with Kim earlier this year in Vietnam.

The summit collapsed without an agreed deal for denuclearising the Korean Peninsula.

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Washington has said it will only relax crippling economic sanctions against the country if North Korea gives up its nukes and long-range missiles.

But North Korea has said it will only scrap its nuclear weapons after sanctions are lifted entirely.

A US special envoy said on Friday the US was ready to hold constructive talks with North Korea to follow through on a denuclearisation agreement reached by the two countries last year.

But the North said on Thursday the United States had become "more and more desperate in its hostile acts" even as it spoke of dialogue.

North Korea's state media KCNA on Friday urged the United States and South Korea to scrap their plans to carry out joint military drills in the summer.

11 Trump and Kim met for the third time today after a last-minute request by the US President Credit: AFP or licensors

11 Kim told Trump it was 'good to meet him' again and he was 'proud' he had come to North Korea Credit: AFP or licensors

11 Earlier Mr Trump and South Korean President Moon Jae-in looked out over the DMZ from an outpost on the southern side Credit: AP:Associated Press

11 Kim has accepted Trump's invitation to meet at the heavily fortified site at the Korean border village of Panmunjom

11 Trump and Kim are seen shaking hands at the summit in Vietnam this year Credit: AP:Associated Press

11 The US President took to Twitter yesterday to ask Kim to 'say hello' and 'shake hands' at the border

11 Trump tweeted that he and Moon had 'toasted' to their new trade deal

South Korea blasts Spaghetti Western tune over DMZ to mock Kim Jong-un

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