Prime Minister Shinzo Abe surged back to power seven years ago, pledging to bolster the nation's defenses in response to a growing threat from China and aiming to amend the pacifist Constitution.

Now on track to become Japan's longest serving prime minister, Abe has kept his first promise. But the second remains elusive.

That means Japan, which U.S. President Donald Trump has criticized over what he called an "unfair" security alliance, still faces limits on acting as a full-fledged American ally.