This didn't strike Japanese territory, but it is a provocation:
North Korea fired two missiles. One blew up immediately after launch -- a common occurrence. Compared to South Korea and the advanced nations it threatens, North Korea's manufacturing base is primitive.
However, the second missile flew 1,000 kilometers then splashed into the Sea of Japan. It was a provocative splash -- one Japan and its allies cannot ignore -- for the missile hit within Japan's maritime Exclusive Economic Zone. Missile tracking data has confirmed the strike location.
Japanese Prime Minister Shinzo Abe called the violation of Japan's EEZ "an intolerable act of recklessness." An EEZ isn't sovereign territory, not quite, but the North Korean test shot amounts to a calculated provocation. Japan has the internationally recognized right to defend its EEZ.
The Japanese government promised a "resolute response," in cooperation with the U.S. and South Korea.
Japan and South Korea are stepping up defensive and offensive capabilities in response to North Korea's persistent threats and growing nuclear capability.
So this is a change in reaction that abandons trying to buy off North Korea.
North Korea's missile launch int the EEZ was a change for them, too.
How much more might they change?