Global nuclear risks surge as arms control treaties collapse and arsenals expand

Global nuclear tensions have risen as key arms control agreements collapse and major powers expand their arsenals. The expiration of the New START treaty in 2023 left the U.S. and Russia without a replacement, while inspections in Iran have stalled since mid-2025. Meanwhile, China, France, and the UK are also upgrading their nuclear capabilities.

The New START treaty, which limited U.S. and Russian nuclear warheads, lapsed in February 2023. No new agreement has taken its place, removing a major safeguard between the two largest nuclear powers. Both nations are now modernising their arsenals, with Russia estimated to hold around 4,400 warheads.

The International Atomic Energy Agency (IAEA) has lost access to Iran’s nuclear sites. No inspections have occurred since U.S. and Israeli airstrikes in June 2025. This lack of oversight means Iran’s current nuclear capabilities remain unchecked. The U.S. no longer holds the upper hand in negotiations with Tehran. China’s nuclear stockpile is growing rapidly, with estimates placing it at roughly 600 warheads. France and the UK are also upgrading their own arsenals. Disarmament talks have stalled, and the 2025 Nuclear Non-Proliferation Treaty (NPT) review conference ended without a joint declaration for the third time in a row.

With no active treaties between the U.S. and Russia, no inspections in Iran, and expanding stockpiles in China, nuclear risks are increasing. The absence of disarmament discussions suggests tensions will likely persist. Major powers continue prioritising modernisation over arms reduction.