The desk of North Korean leader Kim Jong-un.

`The entire US territory is within range of our nuclear weapons and the nuclear button is always on my desk. That is a reality, not a threat,` the Telegraph quoted the leader as saying.

The nuclear powers all maintain a direct chain of command from leaders to combat units.

In fact, to activate the nuclear arsenal, leaders must use complex systems such as the US `nuclear suitcase`.

When wanting to confirm a nuclear attack, the US president must use a card with an authentication code codenamed `biscuit`, which is also an inseparable item of the commander in chief of the US armed forces.

The nuclear suitcase always follows the US president.

`Nuclear button` is a figure of speech intended to simplify this process.

Kim Jong-un’s announcement that he has a nuclear button seems to show that Pyongyang has completed the process of developing nuclear weapons and is ready to put them into service.

`Someone please tell him that I also have a nuclear button, but it’s much bigger and more powerful. And my nuclear button works,` US President Donald Trump responded on Twitter.

Meanwhile, North Korea is believed to possess 10-15 nuclear warheads, along with many types of ballistic missiles from medium range to intercontinental.

Distribution of 14,900 nuclear warheads worldwide

Distribution of nuclear warheads in the world

After the announcement about the nuclear button, the North Korean leader also appeared softer in his speech at the beginning of the year, mentioning the possibility of sending a delegation to participate in the 2018 Winter Olympics, taking place in Pyeongchang,

`Showing off the nuclear button on his desk seems to be just to threaten President Trump, who once called the North Korean leader a little rocket man,` Telegraph writer James Rothwell commented.