Darya Dolzikova​

“Testing has two different implications – the science and the signalling,” says Darya Dolzikova, senior research fellow for proliferation at the Royal United Services Institute...“If Russia or China were to start explosive testing they would be sending a signal of escalating tensions and possibly resorting to nuclear use. In that instance we would be in a very different conversation.”

I expect what he’s responding to are recent tests of nuclear-powered and nuclear-capable missiles by the Russians…but those tests did not include the testing of nuclear weapons, so it’s a bit unclear what he’s actually talking about."

Darya Dolzikova, Senior Research Fellow for Proliferation and Nuclear Policy at the Royal United Services Institute (Rusi) - a London-based defence and security think tank - said she did not believe Trump's comments would change the situation massively. But, she added, "there are other dynamics globally that have raised the risks of nuclear exchange and further proliferation of nuclear weapons to levels higher than they have been in decades". Trump's message, she said, "is a drop in a much larger bucket, and there are some legitimate concerns of that bucket overfilling".