For almost exactly a year, Prime Minister Shinzo Abe saw smooth sailing on diplomacy, visiting 25 countries, meeting leaders from more than 110 countries and making top-level sales campaigns overseas to boost the stagnant domestic economy while avoiding revisions to Japan's official apologies for World War II.

But he flushed his year-long effort down the drain with his surprising visit to contentious Yasukuni Shrine on Dec. 26, the first anniversary of his Cabinet's inauguration in 2012. Criticism poured in from China and South Korea as expected, but also from the United States, which issued an unprecedented statement saying Washington was "disappointed" with Abe's visit to the war-linked shrine.

Although the globe-trotting Abe plans to visit the Middle East, Africa, Switzerland and India in January, experts say 2014 is likely going to be a daunting year for him.