Japan is protected by the USA's nuclear umbrella, and by mutual agreement shouldn't have nukes.
That said, Ukraine is also "protected" by the US thanks to a binding treaty, and we see how that's turned out. Japan has watched events in Ukraine, as well as in China's sphere of influence, and right or wrong their policies reflect their conclusions about US protection.
... and what's Japan's policy, today? They've carefully put together all the ingredients they need to build nukes on very short notice, and continue in that direction. They're glad to be on the US's "friends" list, but they're keeping an insurance policy all the same.
>That said, Ukraine is also "protected" by the US thanks to a binding treaty.
The Budapest Memorandum isn't a binding treaty. A treaty must be ratified by the Senate, but the Budapest Memorandum was just an unratified political agreement. We do however have a formal treaty with Japan that guarantees military assistance.
Furthermore it didn't say anything about the United State's obligations to protect Ukraine with our nuclear umbrella. It only said that the US (along with Russia and Great Britain) would: respect the territorial integrity of Ukraine; not use force, economic pressure, or nuclear weapons against Ukraine; and seek UN Security council action if nuclear weapons were used against Ukraine.
Nowhere does it say we are under any obligation to respond with military force if another country invades Ukraine, it just says we won't invade.
>Japan has watched events in Ukraine, as well as in China's sphere of influence, and right or wrong their policies reflect their conclusions about US protection.
Japan's constitution prohibits production of possession of nuclear weapons - all this as a result of the suffering of Hiroshima and Nagasaki.
That said, Ukraine is also "protected" by the US thanks to a binding treaty, and we see how that's turned out. Japan has watched events in Ukraine, as well as in China's sphere of influence, and right or wrong their policies reflect their conclusions about US protection.
... and what's Japan's policy, today? They've carefully put together all the ingredients they need to build nukes on very short notice, and continue in that direction. They're glad to be on the US's "friends" list, but they're keeping an insurance policy all the same.