Iranian and US officials have just announced that they have agreed to a “set of guiding principles” around a potential nuclear deal following talks in Geneva, but this is only the latest in a set of significant nuclear events. In 2026, discussions of nuclear weapons have gone from sounding hypothetical and dystopian to mainstream. Three key developments are redefining the nuclear state of play.
Expiration of New START
The New START Treaty expired earlier this month. This was the third iteration of the Strategic Arms Reduction Treaty limiting nuclear proliferation between the United States and Russia following the collapse of the USSR in 1991. While already ineffective in many ways since Russia withdrew participation in 2023, the milestone means we are now operating in an era of potentially unconstrained nuclear build-up between the two largest nuclear players. In the past few months, both the United States and Russia have discussed resuming nuclear testing. The increasingly forward nuclear posture of both countries signals a distinct pivot since the New START Treaty first came into effect.
China’s rapid nuclear expansion
In addition to the United States and Russia, China, one of the original five Nuclear-Weapon States under the Non-Proliferation Treaty, has been rapidly building up their nuclear capabilities. A New York Times article this week shares aerial images showing expansion at some of China’s key nuclear sites. From 2015-2025, China more than doubled their nuclear arsenal from 260 warheads to 600. While still far behind the United States' 5,177 nuclear warheads and Russia's 5,459, the rapid rise means China is growing nuclear power and reshaping the global balance.
Iran in flux
Iran’s primary nuclear site was set back by an estimate of up to two years following the US strikes in 2025, but there have been no inspections or reporting from Iran since then and the country has become increasingly unstable. US Special Envoy Steve Witkoff and President Trump’s son-in-law Jared Kushner have held multiple rounds of negotiations with Iran this year to avert military intervention and secure a new nuclear deal. After President Trump withdrew from the Iran Deal in 2018, Iran increased fissile production. Under the former agreement, Iran had a cap of 300kg of uranium enriched to 3.67%. As of the last reporting to the IAEA before the bombing in 2025, Iran had 8,294kg of enriched uranium and 408.6kg enriched to 60%, far beyond the 3-5% required for nuclear energy purposes. It is unclear what deal Witkoff and Kushner may be able to negotiate with any level of confidence in compliance. While both sides acknowledged progress following the talks in Geneva, the United States is still sending a second US aircraft carrier to the region, “in case we don’t make a deal,” as President Trump told reporters.
These three dynamics are changing the realm of global security, and this is not even factoring in North Korea, where we are also seeing an increase in its nuclear arsenal, although we have yet to see concrete action from the second Trump administration to address this issue. Increased sabre-rattling and intense nuclear build-ups are signs we are entering a new nuclear age. A key question for the United States will be whether it takes an interventionalist or isolationist approach to these issues. Based on the track record of the second Trump administration thus far, it seems they will continue to stay engaged as long as there is a sense of traction. If non-proliferation efforts are stymied or reach a stalemate, the administration's response to either turn toward allies or turn inwards will be very telling.
