This year marks the 30th anniversary of the closure of the Semipalatinsk nuclear test site in Kazakhstan, the largest nuclear test site in the former Soviet Union. 

The closure of that site, where more than 450 nuclear tests took place, signaled the end of the era of unrestrained nuclear testing.

Five years later, the Comprehensive Nuclear-Test-Ban Treaty was adopted – a landmark moment for multilateralism and nuclear disarmament. 
 
All told, more than 2,000 nuclear tests are known to have been conducted by eight states, many of them in some of the most remote and pristine environments in the world. They caused enormous human suffering and destroyed ecosystems that will take decades, if not centuries, to heal. 
 
The Comprehensive Nuclear-Test-Ban Treaty bans all explosive nuclear weapons tests anywhere, by any country, and is the centerpiece of global efforts to eliminate nuclear tests once and for all.

This treaty has the power to protect future generations from the human suffering and environmental catastrophe produced by nuclear tests.

The CTBT is an invaluable contribution to nuclear non-proliferation. It is a powerful barrier to the development of new weapons, putting a brake on the nuclear arms race.

But despite its near universal acceptance, the full potential of the CTBT has not been realized, as it has not yet entered into force.
 
I once again urge those states that have not ratified the CTBT to do so without delay. The eight States whose ratifications are necessary for the Treaty to enter into force have a special responsibility. But all States should commit to a legally binding prohibition. 
 
As we mark the International Day Against Nuclear Tests, let us all reflect on the tremendous human and environmental damage caused by decades of nuclear tests.

And let us renew our commitment to end all nuclear tests, by anyone, anywhere.