@MastanKhan the problem is this, everyone jumps on the bandwagon, but when push comes to shove it comes down to infighting.
The Pakistani Army never had a problem finding volunteers, because there's a sense of Patriotism. Pakistan, the Stalwart Islamic Fortress on the Eastern Flank, protecting Islam from the barbaric Hindus & Buddhist.
I'm sure this make-believe Ummah Defense Force isn't going to have a problem recruiting from the poor of Pakistanis. The sense of adventure, of duty, and potential Martyrdom for the protection of ..... the House of Saud?
NATO worked because the Europeans were freaked out over the communists. They had a sense to protect the freedoms they had over the oppression the communists spread. It's one thing to protect the Khana Kaaba, inshaALLAH i'll be there shoulder to should with you, its another to protect a thousand member strong family that came from men who decided to marry anyone and everyone. Edit: And not wear condoms.
They already have a Gulf Defense Shield, let them work out the kinks in their armor. The Roman Armies only became feared after they learned to bulldoze any adversary.