Few experts disagree with David Cameron and Barack Obama's assertion that by paying ransoms Western governments end up bankrolling the very terrorism groups they seek to combat.
But while Britain and the United States might stick assiduously to the principle of non-payment, other countries do not - and ransom cash has come to play a vital role in elevating the Islamic State (Isis) to an international threat, and a very rich one, in just three years. The group is estimated to have generated as much as US$1.5 billion ($1.8 billion) in illicit activities, including kidnapping.
An ancient instrument of warfare, hostage-taking remains a potent, terrifying and highly lucrative weapon.
An investigation by the New York Times has claimed that Islamist groups associated with al-Qaeda have generated up to US$125 million since 2008, trading in hostages from Africa to the Middle East and Asia. More than half this figure was paid in the past year alone - the majority of it by European governments, it is claimed.
Austria, France, Germany, Italy and Switzerland all deny making such payments, but the discovery of documents by a journalist in Mali this year revealed the scale of the problem.