filled at the factory where it was produced. in the prior missile designs, feeling would have to take place shortly before launch so in a battle situation you can imagine an adversary could try to destroy the missiles before they are launched, this advancement in this sense of a fuel ampoule could actually be significant, more significant in terms of survivability of the north korean missiles in the hypersonic aspect. so this is a case where focusing on the hypersonic facet of the test may distract from more important issues that the programme has made possibly quite significant advances, if these reports are true. thank ou for these reports are true. thank you for explaining these reports are true. thank you for explaining that. - that is a researcher in nuclear security at stamford. you are with bbc. still to come, lost and found, a previously unreleased audiotape ofjohn lennon goes under the hammer.