Nuclear weapons are the most powerful bombs, using nuclear fission to release energy, with hydrogen bombs also utilizing fusion. The U. S. dropped the first and only nuclear bombs on Hiroshima and Nagasaki in August 1945, killing tens of thousands immediately and more through radiation. Early nuclear bombs were large compared to modern warheads, which are much smaller and way more powerful.
The Treaty on the Non-Proliferation of Nuclear Weapons (NPT), effective from 1970, recognizes five nuclear-armed countries: the U. S., Russia, Britain, France, and China. These countries can have nuclear weapons, while other nations that signed the NPT promise to use nuclear technology for peaceful purposes. They are also allowed to conduct nuclear research and produce energy. All signatories committed to negotiating for nuclear disarmament.
Aside from the five nuclear powers, four other countries are believed to have nuclear weapons. India tested its first bomb in 1974, followed by Pakistan in 1998. Israel is thought to possess nuclear arms but does not confirm this. North Korea withdrew from the NPT in 2003 and conducted its first nuclear test in 2006.
Concerns exist that if Iran acquires nuclear weapons, Saudi Arabia might follow suit, potentially sparking an arms race in the region. Iran is enriching uranium close to weapons-grade levels but claims its nuclear intentions are peaceful, in line with its rights under the NPT.
Based on a Reuters video, (c) 2026 Thomson Reuters
