(CNN)Here's a look at what you need to know about nuclear nations.
Information about nuclear stockpiles varies from source to source. The information below is sourced to the Nuclear Threat Initiative.
Countries with confirmed nuclear weapons:
China - 250 warheads, 50-75 nuclear capable intercontinental ballistic missiles (ICBMs)
France - Approximately 290 warheads
India - 90-110 nuclear warheads
Pakistan - 100-120 nuclear warheads
Russia - 1,643 warheads on 528 strategic nuclear delivery systems
United Kingdom - Approximately 180 nuclear warheads
United States - 1,642 deployed warheads
Countries with unconfirmed nuclear weapons:
Israel - Suspected to have enough plutonium for 100-200 nuclear weapons
Countries suspected of developing nuclear weapons:
Iran - In 2003, the IAEA released a report about Iran's secret nuclear development over a period of 18 years. The report confirms that Iran has produced small amounts of enriched uranium and plutonium. Iran claims that it is developing nuclear power for peaceful reasons, its right under the 1968 Nuclear Non-Proliferation Treaty.
Iran already has a lot of the building blocks necessary for a nuclear bomb -- such as centrifuges, which are the machines that turn natural uranium into the key ingredient, highly enriched uranium, needed to make a bomb. Iranian officials insist their nuclear program is intended for peaceful purposes. World powers, including the United States, want to curb Iran's nuclear program to keep it from developing a nuclear bomb, and Iran is keen to hold on to as much of its nuclear program as it can.
Countries that have the ability to build nuclear weapons, but claim not to have any nuclear ambitions:
Japan - On November 30, 2006, Japanese Foreign Minister Taro Aso stated that Japan possesses the knowledge and ability to produce nuclear weapons, but has no plans to do so.
Countries that have abandoned nuclear weapons or weapons programs in recent years:
Belarus - Still has civilian nuclear program.
Kazakhstan - Although it inherited nuclear warheads after the collapse of the Soviet Union, Kazakhstan dismantled them.
Ukraine - After the collapse of the Soviet Union, Ukraine had the third largest arsenal of nuclear weapons. The weapons were transferred back to Russia.
South Africa - Became a "non-nuclear weapons state" in 1991.