These are the 9 nuclear-armed countries and the 31 allies they've vowed to defend

The number of nuclear weapons known to exist around the world today is steadily falling, but the fear that a country could one day unleash the most devastating weapon on Earth still persists.

The total number of nuclear weapons fell from 14,465 in 2018 to about 13,885 this year, according to Stockholm International Peace Research Institute's (SIPRI) 2019 yearbook, which was published in June.

It shows that while the international community is working toward the goal of reducing the number of nukes in the world, total elimination is still a long-term reality.

Below is an overview of the world's nine nuclear-armed states, the number of weapons (stockpiled and retired) they have, and the 31 countries they've vowed to protect.