The Mecca Joint Defence Agreement signed between Saudi Arabia, Pakistan and Turkey — between an oil-rich economic powerhouse, the only Islamic country with a nuclear weapon and a NATO member with the second-largest military — is significant. But it lacks the one thing that makes collective defence alliances work: A shared threat. Consider, also, the fact that Pakistan, despite its mutual defence pact with Saudi Arabia last year, has not responded militarily to Iran’s attacks on the kingdom. The Saudis did not help Pakistan, either, when the latter country went to war with Taliban-ruled Afghanistan. The pact will boost defence cooperation, intelligence-sharing and joint production of weaponry.