Japan already had a national security force to help "defend them"..... this isn't really about the military.

what's important to note, is the reconnection of their (militaristic) shinto religious ceremonies with their State gov't and legitimate military again.

Here's a bit of commentary about what this change signifies:
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"But in reading a recent special issue of Gendai shisô (Contemporary Thought) on
Yasukuni, the first article addresses another reason why the shrine is (or should be)
so controversial within Japan itself.
Before and during the war, the shrine was the key institution in the creation and
sustenance of State Shinto as the obligatory, coercive religion of the Japanese state.
Commoner Japanese were taught in school and elsewhere that the greatest good they
could achieve was to die for the emperor in battle, the reward for which merit would
be enshrinement as a "nation-protecting god" at Yasukuni. This raising of self-sacrifice
in war for the emperor to the level of highest value is often understood to be one of
the most important elements in the establishment of agressive militarism in Japan.

When the Americans sought a socio-political-cultural reform of Japan after the war,
a reform which was meant to ensure that Japan would not become a militarist society
again, one of their key goals was to enforce the principle of separation of church and
state. So the postwar constitution establishes the principle in unambiguous terms and
Yasukuni shrine was allowed to survive as a private religious organization. In the
domestic context, the enshrinement of the Class-A war criminals as gods is considered
unfortunate, but the more important principle is that the State and the Shrine must
have no official connection whatsoever. Under the principle of freedom of worship, in
other words, the shrine can do whatever it wants in terms of worship, but any time
any representative of the State (whether an individual or an organ thereof) engages
with the Shrine in an official capacity, a founding principle of the postwar bulwark
against the return of prewar militarist fascism is violated. That, for Japanese critics, is
the core issue." blog

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