Israel is widely believed to possess nuclear weapons and per a 1993 report, chemical and biological weapons of mass destruction. Israel has not signed the Treaty on the Non-Proliferation of Nuclear Weapons and maintains a policy of deliberate ambiguity toward its nuclear capabilities. The Israeli Navy's Dolphin submarines are believed to be armed with nuclear Popeye Turbo missiles, offering second-strike capability. Since the Gulf War in 1991, when Israel was attacked by Iraqi Scud missiles, all homes in Israel are required to have a reinforced security room, Merkhav Mugan, impermeable to chemical and biological substances.