Experts have calculated North Korea's missile range has widened, technically putting all of New Zealand now within reach.
The rogue nation launched a ballistic missile on Wednesday morning (NZ time), landing within 370km of Japan's coast.
Experts have since bumped up the country's intercontinental range from an estimated 10,000 kilometres, capable of reaching Auckland, to 13,000 kilometres - which could reach even Stewart Island.
The missile travelled 1000 kilometres, staying airborne for 54 minutes and reaching a height of 4500 kilometres, co-director of the global security program at the Union of Concerned Scientists David Wright says.
It is thought to have been fired almost straight up in the air - but if it was fired on a standard trajectory to maximise reach, could have gone a lot further.
"This is significantly longer than North Korea's previous long-range tests, which flew on lofted trajectories for 37 minutes and 47 minutes," Mr Wright said.
"Given the increase in range it seems likely that it carried a very light mock warhead. If true, that means it would be incapable of carrying a nuclear warhead to this long distance, since such a warhead would be much heavier."
Auckland is 9,810 kilometres from Pyongyang.
Washington DC, home to president Donald Trump, as well as New York City, are now also thought to be within reach.
Kim Jong-un has previously stated a goal of being able to strike the United States mainland.
Prime Minister Jacinda Ardern has previously told The Nation North Korea is "absolutely a genuine and real threat" and New Zealand is ready to play a role if requested.
"Every [world leader] needs to ... put pressure on Pyongyang to make sure they are responding to the sanctions and messages coming from the international community."
All options are being explored by the New Zealand Government, Ms Ardern says, but she remains firm military intervention is a last resort, and only if it had United Nations support.
"One of the reasons we're so firm on that is we're yet to exhaust all of the channels that we have."