Is the world back to testing nuclear weapons? Here are the facts

David Michael Lamb · CBC News

· Posted: Nov 01, 2025 4:00 AM EDT | Last Updated: November 3

The investigating of atomic weapons is abruptly a large taxable of treatment aft being mostly dormant for 3 decades. Last week, Russia tested a nuclear-powered missile, but did not detonate an existent bomb. In response, President Donald Trump said this week the U.S. volition resume investigating atomic weapons.

So acold successful the 21st century, the lone state to person conducted atomic weapons tests is North Korea, and those tests person each been underground. The U.S. past tested a atomic weaponry successful 1992. Russia’s past trial was successful 1990. China stopped successful 1996. 

The astir spectacular atomic tests were those conducted successful the unfastened aerial successful the precocious 1940s and 1950s, producing immoderate of the astir iconic and horrifying images of the atomic age. The mushroom unreality has been a awesome of the menace ever since.

The devastating effects of those tests are inactive being felt. The U.S. tests connected Bikini Atoll successful the Pacific were immoderate of the biggest ever. To this day, contamination from radioactive fallout makes it unsafe for anyone to unrecorded determination permanently.

An atomic weaponry trial detonation disconnected Bikini Atoll, Micronesia successful 1946. (Keystone/Getty Images)

Most atmospheric investigating ended successful 1963, erstwhile the Partial Test Ban Treaty was agreed by the U.S., Soviet Union and others. It didn’t see circumstantial ways of verifying whether anyone violated it, but it proved to work. The U.S. and the Soviets some halted the signifier and ne'er returned to it. However, France continued investigating supra crushed until 1974, and China until 1980.

What brought investigating to a implicit halt (almost)

Underground investigating continued by each the large powers done the 1980s, which constricted the dispersed of radioactive fallout. However, a question was gathering to halt the signifier entirely.

In 1992, the U.S. imposed its ain moritorium connected testing. Then successful 1996, the Comprehensive Nuclear-Test-Ban Treaty (CTBT) was passed by the United Nations. It banned each atomic trial explosions anyplace successful the atmosphere, successful the water oregon underground.

As portion of the treaty, a planetary monitoring strategy was acceptable up to observe immoderate atomic tests. Hundreds of sites astir the satellite measurement seismic activity, dependable waves successful the water and radiation successful the atmosphere. That mode nary state is capable to behaviour a atomic trial connected the sly. This strategy has detected each of North Korea’s tests.

However, the CTBT lone goes truthful far. It hasn't officially travel into unit due to the fact that not capable countries person ratified it. They see each the large atomic powers and immoderate others: the U.S., Russia, China, India, Pakistan, Israel, Iran, Egypt and North Korea.

WATCH | Trump moves to restart atomic weapons testing:

Although Russia and China person not conducted immoderate large-scale atomic explosions successful caller years, the U.S. State Department says it’s imaginable that some countries person done smaller tests that would technically interruption the moratorium. 

In 2023, Mikhail Kovalchuk, an advisor to Russian President Vladimir Putin, said Russia should trial a atomic limb erstwhile a twelvemonth successful bid to “scare the West.” But truthful acold there’s nary denotation that has happened.

So, atomic investigating is back?

At slightest successful part, yes. The Russian trial past week was for a nuclear-powered rocket that could besides transportation a atomic warhead. Putin claimed it has virtually unlimited range, could not beryllium tracked and would beryllium intolerable to intercept. Russia besides conducted drills with intercontinental ballistic missiles and cruise missiles, some of which tin present atomic bombs.

Then connected Wednesday, it emerged that Russia has tested an underwater drone that tin present a almighty atomic onslaught connected a coastal city. The details dependable similar they travel from an enactment movie. The drone, called Poseidon, is designed to detonate adjacent the coastline and unleash a almighty radioactive tsunami connected a ample municipality centre. Again, Putin, who archetypal announced its beingness successful 2018, claimed the drone would beryllium excessively accelerated to way oregon intercept.

Russia's Poseidon nuclear-capable strategy is seen successful this inactive representation taken from an animated video released successful 2018. (Russian Defence Ministry/Reuters)

As for the U.S., it depends connected what Trump means precisely by resuming testing. It’s not yet wide whether helium is referring to rocket tests akin to what Russia is doing, oregon existent atomic detonations.

This past April, the National Nuclear Security Administration, which is liable for the U.S. stockpile, said it is acceptable to resume underground investigating if ordered, but it saw nary request to bash so.

Trump’s announcement this week besides clashes with what helium said lone a fewer months ago. In August helium said helium wanted to unfastened talks with Russia and China to trim oregon adjacent destruct the atomic threat. “We can't fto atomic weapons proliferate. We person to halt atomic weapons. The powerfulness is excessively great," Trump said.