New Delhi, June 12 -- Rene Mayrhofer, a senior Android security official, has quit Google after the tech giant signed a contract giving the US Department of Defense access to its artificial intelligence systems for classified military work.

A senior Google director has resigned in protest over the company's decision to supply artificial intelligence technology to the US military, saying the move made his departure "unavoidable" and that leadership had abandoned the ethical principles that once defined the company.

Rene Mayrhofer, director for Android platform security, confirmed to Business Insider that he had circulated a farewell letter to colleagues on 18 May, in which he accused Google's top leadership of quietly reversing its commi...