The recent killing of Mohsen Fakrizadeh, the “father of Iran’s nuclear program,” is another in a long series of attempts to disrupt Tehran’s dogged drive for nuclear weapons. These strikes, which have ranged over decades, have included the killings of Iranian nuclear scientists, cyberattacks on the Iranian nuclear program, and mysterious explosions at the regime’s nuclear sites. Yet no one, including the US, has conventionally attacked Iran’s nuclear sites despite the clear and present danger posed by a nuclear Iran to American national interests and general international security. Why not?