• In “A bomb to bust the deepest bunkers” (16 July, p 30) we attributed a comment to Michael Levi of the Brookings Institution in Washington DC. In fact, Levi is with King’s College London. And despite our preamble to his quote, Levi does not “see the need” for the new weapon. When he said: “Increased penetration is more important for chemical and biological agent-destroying weapons than other bunker busters,” he was referring to what had led Pentagon engineers to develop the weapon in question, rather than his own belief.
