China aggression was largely the reason India pursued nuclear weapons.

From Wikipedia:

India's loss to China in a brief Himalayan border war in October 1962, provided the New Delhi government impetus for developing nuclear weapons as a means of deterring potential Chinese aggression.

And of course Pakistan pursued nuclear weapons because India had them. This is how nuclear proliferation works.

Your thinking is dangerously naive. China hasn’t pursued India because of India’s nuclear deterrent.

US guarantees of security for Japan and Taiwan are partially due to an attempt to reduce nuclear proliferation.

US involvement has been critical to Taiwanese independence going all the way back to the 1950’s when China invaded ROC held islands.

https://en.m.wikipedia.org/wiki/First_Taiwan_Strait_Crisis

The US deployed nuclear weapons to Taiwan during a crisis caused by China in the Taiwan Straights in the 1970’s.

* During the Cold War, the United States deployed nuclear weapons on Taiwan as part of the United States Taiwan Defense Command. In 1972, United States president Richard Nixon ordered nuclear weapons to be removed from Taiwan and this was implemented by 1974. Nuclear weapons are known to have been stored at Tainan Air Force Base.*