Donald Trump recently boasted that he has a bigger and more powerful 'nuclear button' than North Korean leader Kim Jong Un.

The truth, however, is the president does not have a nuclear button on his desk at all.

Instead, Trump has access to a 20kg (45lb) briefcase, known as the 'nuclear football', that is kept close to the president at all times.

Inside is a guide for carrying out a nuclear strike, alongside a list of locations that can be targeted by the country's arsenal of 900 nuclear weapons.

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Donald Trump has boasted that he has a bigger and more powerful 'nuclear button' than North Korean leader Kim Jong Un - but the US president does not actually have a physical button

HOW THE PRESIDENT FIRES A NUKE The process for launching a nuclear strike is secret and complex and involves the use of a portable device housed in a bulky briefcase. 1 - Get out the biscuit: If the president were to order a strike, he would first need to verify his identify with codes unique to him. The codes are recorded on a card known as the 'biscuit' which is carried by the president at all times. New codes are provided each day by the National Security Agency. 2- Access the 'football': He would then access the 'football' briefcase containing secure communications equipment as well as instructions on how to verify his identity and transmit the command. 3 - Order an attack: The launch order would be transmitted to the Pentagon and Strategic Command via a radio transceiver within 'the football'. The secretary of Defense is told about the order, but does not have the power to veto it. Advertisement

Trump's most recent nuclear threats came after Kim's new year address, in which he cautioned: 'The US should know that the button for nuclear weapons is on my table.'

Trump mocked the claims, tweeting on Tuesday: 'Will someone from his depleted and food starved regime please inform him that I too have a Nuclear Button, but it is a much bigger & more powerful one than his, and my Button works!'

If the president were to order a strike, he would first need to verify his identify with codes unique to him.

The codes are recorded on a card known as the 'biscuit' which is carried by the president at all times.

New codes are provided each day by the National Security Agency.

The biscuit has several fake codes, so the president has to memorise the location of the correct codes on the card.

He would then access the 'football' briefcase containing secure communications equipment as well as instructions on how to verify his identity and transmit the command.

The launch order would be transmitted to the Pentagon and Strategic Command via a radio transceiver within 'the football'.

The secretary of Defense is told about the order, but does not have the power to veto it.

The system is able to launch within minutes of the president’s order, according to Quartz.

It is unclear how Trump's counterpart in North Korea would launch a strike, as the Kim's nuclear procedure is shrouded in mystery.

While Kim claimed in his New Year address that 'the whole territory of the US is within the range of our nuclear strike', it remains unclear whether the nation's weapons could actually reach US soil.

Intercontinental ballistic missiles tested by North Korea in July 2017 are likely capable of reaching 3,400 miles (5,500 km), which could reach a US Naval Base in Guam.

Pyongyang is subject to multiple sets of United Nations sanctions over its atomic and missile programs, which it says it needs to protect itself against a possible invasion.

Instead of a stationary button, the president would use a portable gadget housed in a briefcase to launch a nuclear strike. The 20 kg (45 lb) device has been nicknamed the 'nuclear football' (pictured) because it is carried by a rotating group of military officers everywhere Trump goes

NORTH KOREA'S NUCLEAR ARSENAL While North Korean leader Kim Jong Un claimed in his new year address that 'the whole territory of the US is within the range of our nuclear strike', it remains unclear whether the nation's weapons could actually reach US soil. Intercontinental ballistic missiles tested by North Korea in July 2017 are likely capable of reaching 3,400 miles (5,500 km), which could reach a US Naval Base in Guam. Pyongyang is subject to multiple sets of United Nations sanctions over its atomic and missile programs, which it says it needs to protect itself against a possible invasion. This November photo shows the launch of the Hwasong-15 missile, which North Korean leader Kim Jong Un claims is capable of reaching 'the whole territory of the US' It regularly issues threats against its 'imperialist enemy' Washington, and has long sought a rocket capable of delivering a warhead to the continental United States. The progress has accelerated in recent years after young leader Kim Jong-Un took power following the death of his father, longtime ruler Kim Jong-Il, in 2011. Pyongyang has staged six atomic tests - including two last year - with the regime stepping up efforts to produce a nuclear warhead small enough to fit into a missile. Advertisement

It regularly issues threats against its 'imperialist enemy' Washington, and has long sought a rocket capable of delivering a warhead to the continental United States.

The progress has accelerated in recent years after young leader Kim Jong-Un took power following the death of his father, longtime ruler Kim Jong-Il, in 2011.

Pyongyang has staged six atomic tests - including two last year - with the regime stepping up efforts to produce a nuclear warhead small enough to fit into a missile.

Despite Trump ratcheting up tension with North Korea, he would not use a physical button to launch a nuclear attack. The process for launching a strike is secret and complex and involves the use of a portable device housed in a bulky briefcase

In his annual New Year speech, Kim Jong Un warned America that he has a 'button' for nuclear weapons. Trump mocked the claims on Twitter on Tuesday

Earlier on Tuesday, Trump sounded open to the possibility of an inter-Korean dialogue after Kim made a rare overture towards South Korea in his new year speech.

But Mr Trump's ambassador to the United Nations insisted talks would not be meaningful unless the North was getting rid of its nuclear weapons.

In a morning tweet, Trump said the US-led campaign of sanctions and other pressure were beginning to have a 'big impact' on North Korea.

If the president were to order a strike, he would identify himself to military officials at the Pentagon with codes unique to him. Pictured is a photo taken of the 'Knothole' US nuclear test detonated in the Nevada desert in 1953

He referred to the recent, dramatic escape of at least two North Korean soldiers across the heavily militarised border into South Korea.

He also alluded to Kim's comments on Monday that he was willing to send a delegation to the Winter Olympics, which will be hosted by South Korea next month.

'Soldiers are dangerously fleeing to South Korea. Rocket man now wants to talk to South Korea for first time. Perhaps that is good news, perhaps not – we will see!' Trump wrote, using his derisive nickname for the young North Korean leader.