Putin has reminded the world Russia is a nuclear power. Pic: AP. Source: AP

Nuclear weapons have only been deployed twice in the world’s history — in Hiroshima and Nagasaki in 1945 — in a moment that saw leaders collectively vow to never use them again.

However this week, the terrifying prospect has reared it’s ugly head after Russian President Vladimir Putin told pro-Kremlin youth the world shouldn’t “mess” with Russia.

“I want to remind you that Russia is one of the leading nuclear powers,” he reportedly told a group of youngsters near a lake outside Moscow.

MORE: Putin talks nuclear power as he tells the West to back off

It comes after weeks of aggressive actions against Ukraine, which Western leaders are taking seriously. After imposing strict sanctions, members of the international military alliance NATO will amass a “spearhead” force of 4000 troops that can be rapidly deployed to the region.

So who really has what in terms of a nuclear arsenal?

Sources: Nuclear Threat Initiative, Federation of American Scientists, Arms Control Association. Graphic: Ron Erdos. Source: Supplied

GLOBALLY: It’s estimated there are about 22,000 nuclear weapons in the world today according to the UN Office for Disarmament Affairs. However it’s a number that is virtually impossible to verify as estimates are based on self-reporting and most countries cloak their nuclear programs in intense secrecy. It’s also made even more complicated by the fact that some weapons are due to be dismantled and not considered in active use.

It’s estimated North Korea has 6-10 nukes in their arsenal. Source: AFP

The Federation of American Scientists puts the total number closer to 16,300, with the US and Russia containing 93 per cent of the global stock. They estimate about 10,000 weapons are in nuclear arsenals with others retired and waiting to be dismantled. Around 4000 are available with 1800 on high alert ready for use at short notice, according to the organisation.

Five countries are officially recognised as having the weapons under the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) including China, Russia, France, the UK and US. Here’s a breakdown of exactly who has what.

UNITED STATES: The US is the only country that has used nuclear weapons in the past — against Japan in 1945. Its nuclear arsenal peaked in 1967 at 31,255 warheads although this has since been reduced to 4804 warheads according to latest government disclosures in September 2013, reported by the Nuclear Threat Initiative (NTI), a non-profit organisation concerned with reducing the spread of weapons.

However it also has “several thousand” that have not been dismantled and about 200 weapons stored in Belgium, Italy, Germany, the Netherlands and Turkey.

Obama has committed to reducing the number of nuclear warheads to zero. Pic: AP. Source: AP

RUSSIA: There is “considerable uncertainty” surrounding the sites of Russia’s nuclear weapons according to the Federation of American Scientists. However NTI estimates Russia has 1512 strategic warheads ready to be deployed with a total number between 8500 and 10,000 warheads and another 3000 waiting to be dismantled.

CHINA: China is also seriously secretive about its nuclear weapons, even using underground storage facilities to conceal equipment. It’s estimated the country has 250 warheads in 12 locations, according to the Federation of American Scientists.

FRANCE: France has 290 nuclear warheads, which are thought to be stored in six locations around the country.

Russia is estimated to have the largest global stockpile of weapons. Source: AP

UNITED KINGDOM: The UK has fewer than 225 nuclear warheads, all of which can be launched by sea. It’s part of the NPT and is committed to scaling back its nuclear program.

INDIA: India regards its weapons as a crucial part of strategic defence and is not party to the NPT. It’s estimated to have between 90 and 110 warheads.

PAKISTAN: Is also outside the NPT and has 100-120 nuclear warheads. It has agreed to provide India with advance notice of tests.

North Korea has conducted three nuclear tests and is thought to have up to 10 nuclear bombs. Pic: AFP. Source: AFP

ISRAEL: Israel is committed to a policy of “opacity” when it comes to nuclear weapons and has never admitted to having them, but is widely believed to have between 100-200 nuclear warheads.

NORTH KOREA: It’s not known for sure how many nuclear weapons North Korea has but the country has conducted three explosive tests and is thought to have enough enriched uranium for 6-10 weapons.

A demonstrator protests nuclear weapons ahead of the upcoming NATO summit in Wales. Pic: AFP. Source: AFP

IRAN: Has an advanced nuclear program, which it says is peaceful. However failure to report certain parts of it to the International Atomic Energy Agency has led to fears it is covertly developing nuclear weapons and the UN Security Council has passed resolutions demanding the country stop enriching uranium immediately.

SYRIA: No confirmed weapons but has reportedly received assistance from Russia, China and Iran to develop a weapons of mass destruction program.