Oh, that can't be much of a problem; the United States does choose to export a lot of its advanced weapons systems to allies (and occasionally to not-so-allied nations). The only stop sign on that road in recent times has been the F-22A Raptor fighter aircraft... which the Obama administration chose to cease production on rather than to extend manufacturing to allow an export market ...because that aircraft is deemed so highly sensitive that not even America's closest allies like Japan and Australia could be trusted to guard its secrets. (Don't even ask if the Israelis were in line to buy some.)
Japan is the co-producer of the Standard SM-3 Block 2A, the current American and Japanese naval Ballistic Missile Defense interceptor...
And since Japan has had a *no-weapons-export-to-anyone* policy since 1976, with a single exception put in place in 1983: sales to the United States...
...then there can't be a problem when along comes U.S. SecDef Robert Gates to ask Japan to export the SM-3 to third countries in support of the Obama administration's new "plan" for BMD in Europe, can there?
chotto matte (Jp: "wait a moment")
When you need our manufacturing to make part of a system, we're your trusted pal. As we then must trust you as well, of course we'll deliver the system to whomever you think should get it.
When we need the best fighter-interceptor available to replace a whole lot of aging aircraft *which by the way defend your bases here as well*, then we are unworthy of being trusted with the F-22A.
Given that being the current relationship, explain to me please *WHY* we should change our laws for your benefit again.
And they wonder back in Washington D.C. why various Defense negotiations go sideways.