Apple garnered widespread Internet applause this week for refusing to build a backdoor into its iOS operating system when requested to do so by the FBI. The FBI had hoped to gain access to an iPhone used by Syed Rizwan Farook, one of the perpetrators of last December’s shooting in San Bernardino, but Apple has thus far not complied, citing grave security as well as legal concerns. On February 16th, Apple CEO Tim Cook published a letter to Apple’s customers outlining the tech company’s position, claiming that building a new unsecure operating system to unlock a single iPhone would, firstly, undermine the security of millions of other iOS devices, and secondly, set a “dangerous precedent” legally by vastly expanding the reach of the U.S. government. The ACLU, the EFF, and many on Reddit agree. Apple has since posted a follow-up FAQ, answering further questions about its position, and the director of the FBI has fired back with a public letter of his own. Amid fierce public debate over encryption, privacy, and national security, Apple’s letter has already become a spark for further debate.