If you're gonna be THAT ruthless you don't need to nuke Mecca, you need to occupy it. Force the Muslims to take up arms, form armies and become concentrated targets for nukes, followed by mop ups from combined arms - taking no prisoners. Also hit their population centers.
Also need to occupy resource areas (i.e. oil fields) and exterminate or expel all potential enemies.
Don't think we can be the ruthless.
Are you familiar with the term Jannisaries, the troops recruited from Christian communities used to control conquered populations? It was a term for the forces organized by Turkish Musselman Bey Murad I in the late 14th century, those occupation forces remaining effective until 1826, altogether about 450 years.