Nuclear weapons A new Danger To the World: Nuclear weapons if they will be in the hands of wrong countries then they gonna destroy us .What are the threats today we are facing is being named nuclear proliferartion. for more details read below

Nuclear proliferation is a term used to describe the spread of nuclear weapons, fissile material, and weapons-applicable nuclear technology and information, to nations which are not recognized as "Nuclear Weapon States" by the Treaty on the Nonproliferation of Nuclear Weapons

Why Opposed By Governments

Proliferation has been opposed by many nations with and without nuclear weapons, the governments of which fear that more countries with nuclear weapons may increase the possibility of nuclear warfare

Nuclear warfare (sometimes atomic warfare or thermonuclear warfare), is a military conflict or political strategy in which nuclear weaponry is used to inflict damage on an opponent.
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion. Both reactions release vast quantities of energy from relatively small amounts of matter.
 Compared to conventional warfare, nuclear warfare can be vastly more destructive in range and extent of damage, and in a much shorter time scale. A major nuclear exchange could have severe long-term effects, primarily from radiation release, but also from the production of high levels of atmospheric pollution leading to a "nuclear winter" that could last for decades, centuries, or even millennia after the initial attack.  A large nuclear war is considered to bear existential risk for civilization on Earth.
Only two nuclear weapons have been used in the course of warfare, both by the United States near the end of World War II. On August 6, 1945, a uranium gun-type device (code name "Little Boy") was detonated over the Japanese city of Hiroshima. Three days later, on August 9, a plutonium implosion-type device (code name "Fat Man") was detonated over Nagasaki, Japan. These two bombings resulted in the deaths of approximately 200,000 Japanese people (mostly civilians) from acute injuries sustained in the detonations.^[5]

Hence this nuclear proliferation can de-stabilize international or regional relations, or infringe upon the national sovereignty of states.

Nuclear Weapon States

There are currently eight states that have successfully detonated nuclear weapons. Five are considered to be "nuclear-weapon states" (NWS) under the terms of the Nuclear Non-Proliferation Treaty (NPT). In order of acquisition of nuclear weapons these are: the United States, Russia, the United Kingdom, France, and China. Nations that are believed to possess nuclear weapons are sometimes referred to as the nuclear club.

Since the NPT entered into force in 1970, three states that were not parties to the Treaty have conducted nuclear tests, namely India, Pakistan, and North Korea. North Korea had been a party to the NPT but withdrew in 2003. Israel is also widely believed to have nuclear weapons, though it has refused to confirm or deny this, and is not known to have conducted a nuclear test.^[1]
South Africa has the unique status of a nation that developed nuclear weapons.
Efforts made in this field

The establishment of an "international atomic development authority," which would actually own and control all military-applicable nuclear materials and activities

The creation of a system of automatic sanctions, which not even the U.N. Security Council could veto (power to stop an official action ), and which would proportionately punish states attempting to acquire the capability to make nuclear weapons or fissile material.

But the Soviet Union planned to veto it in the Security Council Thus the above ways failed to emerge.