Do the United States and its allies really have the technology to stop incoming missiles from North Korea?

In the week North Korea tested another ballistic missile - this time it flew over northern Japan - David Aaronovich asks what threat does North Korea's missile programme pose?

And beyond North Korea, what are the capabilities of ICBMs? And how effective are missile defence systems?

Contributors:

Sir Lawrence Freedman, Emeritus Professor of War Studies at Kings College London

Joseph Cirincione author of Nuclear Nightmares: Securing the World Before It Is Too Late

Dr Patricia Lewis, a former UN official who specialised in non-proliferation

Dr Laura Grego from the Union of Concerned Scientists.