My standard is pretty simple; can a nation's military battle 1 million Chinese PLA troops, the standard bad guys of our time, and win? Just three countries can say yes to this question; the US, Russia, and Korea. India may win a limited conflict, but would have trouble stopping the advances of 1 million PLA troops in an all out war.
Korea has an unusually powerful military for a country of its size because of the legacy of the Korean War; the primary combatant for the ROK from 1951 to 1953 was the PLA, and the Korean military was designed to battle a combined North Korean-Chinese force of 1.5 million troops in the event of the resumption of the Korean War.
1. Nuclear weapons are useless in almost all war scenarios unless the nuclear state is facing a total destruction similar to Germany and Japan of 1945, and may wish to take out its enemy with it to hell.
2. Aside India, Pakistan doesn't present a military threat to anyone else.
Philippines have a lot of people to be conscripted, as opposed to Sweden short on population.
Weapons of the last resort upon a state's impending doom and total annihilation. Nukes are tactically useless for all other cases, and the Soviets and Americans would have just nuked Taliban to end their Afghan wars if possible instead of losing tons of troops and equipment.