Japan recently returned a large quantity of weapons-grade plutonium to the US -- sufficient to start its own nuclear weapons program -- but only after it had broken ground on a plant that would enable the country to enrich its own "suspiciously large" stockpile of plutonium.
Japan's space agency, JAXA, uses solid-fuel rockets. This choice limits the size of payloads JAXA launch, but it's ideal for nuclear missiles.
"The success rate of 95% of the H-2A is on a par with 96.4 percent for the Atlas V of the United States and 94.9 percent for the European Ariane 5"
The much smaller Japanese Mu series is a solid space launcher and provides a much better technology base for missiles. http://en.wikipedia.org/wiki/Mu_%28rocket%29
Here's a list of various Japanese launch systems and their success rates.
System - success - fail - percent success
- Epsilon - 1 - 1 - 100%
- GX - 0 - 0 - (abandoned)
- H-1 - 9 - 9 - 100%
- H-2 - 5 - 1 - 80% (or 60%, one of the successes was a partial failure)
- H-IIA - 23 - 1 - 95.7%
- H-IIB - 4 - 4 - 100%
- J-I - 1 - 1 - 100% (then abandoned)
- Lambda 4 - 9 - 5 - 44%
- Lambda 4S - 5 - 4 - 20%
- M-V - 7 - 1 - 85%
- N-I - 7 - 1 - 85%
- N-II - 8 - 0 - 100%
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.
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's constitution prohibits production of possession of nuclear weapons - all this as a result of the suffering of Hiroshima and Nagasaki.
http://en.wikipedia.org/wiki/Japan's_non-nuclear_weapons_pol...
"Between 1954 and 1972, 19 different types of nuclear weapons were deployed in Okinawa, but with fewer than around 1,000 warheads at any one time."
That is not in conflict with that other page. Okinawa wasn't part of Japan between 1945 and 1972. See http://en.wikipedia.org/wiki/1971_Okinawa_Reversion_Agreemen....
"In 1999 and 2002, The Japan Times and the Okinawa Times reported speculation that not all the supposed weapons were removed from Okinawa."
May be true, but as stated, just unconfirmed rumor.
"In an interview with the Mainichi Shimbun in 1981, Edwin O. Reischauer, former U.S. ambassador to Japan, said that U.S. naval ships armed with nukes stopped at Japanese ports on a routine duty and this was approved by the Japanese government."
So, it seems the USA got permission to have nuclear weapons aboard ships in Japanese ports. There also may still be nuclear weapons on Okinawa (not that unlikely, I would say, but that's pure speculation)