Obviously you mean Russia, but China, North Korea, and Iran also have an interest in weakening NATO.
Australia may not be in NATO, but there's close coordination anyways.
Pick a fight with Australia and the ANZUS Treaty comes into force, and if the ANAZACs are in a fight, the US and UK will almost certainly be involved.
Nuke Japan? You've picked a fight with NATO. Invade Australia? Same deal.