An opinion poll in New Zealand in 1991, showed 54% of those sampled preferred to let the treaty lapse rather than accept visits again by nuclear-armed or nuclear-powered vessels. The policy did not become law until 8 June 1987 with the passing of the New Zealand Nuclear Free Zone, Disarmament, and Arms Control Act 1987, more than two years after the "Buchanan" was refused entry after the US refused to declare the presence or absence of nuclear weapons, and a year after the US suspended its treaty obligations to New Zealand. This law effectively made the entire country a nuclear-free zone. Despite the ANZUS split, Secretary of State George P. Shultz maintained that the ANZUS structure was still in place, should NZ decide in the future to reverse its anti-nuclear policy and return to a fully operational defence relationship with the US. President Reagan also maintained in "NSDD 193" (National Security Decision Directive) that New Zealand still remained a "friend, but not an ally".