After Labour leadership candidate Owen Smith suggested talks with militant groups such as Isis might be an option, Rear Admiral Chris Parry has warned this would give the group moral legitimacy.
Smith's suggestion was heavily criticised, with Jeremy Corbyn's campaign team labelling his remarks “hasty” and “ill-considered”.
Parry, a strategic forecaster, told Julia Hartley-Brewer what he believes needs to be done.
"We need to deal with them in their territorial base," Parry said. "We then need to deal with their criminal networks and the terrorist networks that have fanned out into various franchises, and most importantly we need to bring to justice the people who've been involved.
"You've going to give these people moral legitimacy if you think they're worthy of negotiation," he added.
"The real problem is we have politicians who are good at winning elections but are not good at doing strategy.
"Across the whole of the country we need to invest in strategy, we need to think long term," he explained. "We can't sit in this offshore island that we have and expect in a globalised world that things won't come to us because of distance."
Listen to the full interview to find out more