Most close observers of the relationship agree that the U.S.-Japan alliance is in much better shape today than 15 years ago. Nonetheless, the alliance faces three major challenges in a new external environment. One is North Korea, whose recent behavior has been clever and deceptive. A second challenge for Japan is the dramatic rise of China's economy. Third, the U.S.-Japan alliance will have to face a new set of transnational challenges to our vital interests, such as pandemics, terrorism, and human outflows from failed states. Chief among these challenges is the threat posed by global warming, with China having surpassed the U.S. as the leading producer of carbon-dioxide emissions (though not in per capita terms).
Nye, Jr., Joseph S. "Will US-Japan Alliance Survive?" Korea Times, July 14, 2009.