An "Arab NATO" already exists and has historically proven itself useless. The Joint Defense Council of the Arab League was established in 1950 to coordinate the joint defense of the Arab League member states. The Arab League voted in 2007 to reactivate the their joint defense arrangement and establish a peacekeeping force to deploy in South Lebanon, Darfur, Iraq, and other hot spots. It's still useless.
At a 2015 summit in Egypt, member nations agreed in principle to form a joint military force.Trump to unveil plans for an ‘Arab NATO’ in Saudi Arabia
By Josh Rogin
May 17 - 6:00 AM EDT
The Washington Post