Many Chinese do not think the Japanese leadership has fully accepted the country's responsibility for the invasion of China in the 1930s and 1940s. Chinese students learn about the widespread atrocities committed by Japanese forces in gory detail, while Japanese nationalists play down the details and China says many Japanese textbooks whitewash the invasion - all of which means there's been no real reconciliation. China and Japan also have a long-running territorial dispute over control of the Senkaku/Diaoyu islands in the East China Sea arising out of the first Sino-Japanese war of the modern era in the 1890s. The islands were annexed by Japan after that war in 1895, but 50 years later, after the Second World War, unlike other territories conquered by the Japanese, they were not returned to China, but instead occupied by the Americans. By the time the United States decided it didn't need the islands in the early 1970s, China was ruled by the Communist Party and Japan was a US ally, so Washington returned the islands to Japanese control.
Growing more powerful in recent years, China has increased pressure on Japan to acknowledge there is a dispute over the islands. China now regularly sends ships and planes to patrol near the islands, the Japanese respond with patrols of their own, and the likelihood of an accidental clash is increasing.
So even if comparisons with 1914 are off the mark, conflict between China and Japan could still be a possibility.
Abe is a seen as a nationalist who would like Japan to move on from the pacifism imposed on it by the United States after 1945. He may not go as far as changing the pacifist elements of the constitution, but he wants to change Japan's defense posture, so the armed forces take a more assertive role - up to now, Japan has relied heavily on the United States to defend the areas around it - and he justifies this by pointing at China's growing military capabilities and doubts over Beijing's intentions.
In Beijing, Xi is focused on reforming the economy and cleaning up the corruption that's undermining the Communist Party's legitimacy, which would suggest he does not want a war. But for his reforms to succeed, maintaining tension with Tokyo and a sense of threat from abroad is useful as it encourages loyalty to the center. Xi will also need support of the military and security apparatus for his reforms as he takes on vested interests in the party leadership, provincial governments and large state enterprises, and this makes compromise with Japan more difficult. Chinese public opinion is also hostile to Japan, evident in opinion polls, social media and the ease with which anti-Japanese boycotts occur.
So, domestic politics as well as geopolitics are driving both China and Japan to be more assertive, and this worries Washington. When Abe visited the controversial Yasukuni shrine for Japanese war dead at the end of December, it not only stoked tension with China and South Korea which issued strong protests, the United States publicly stated it was "disappointed."
In his comments at Davos, Abe, presumably thinking of the strong trade links between his country and China, said the economic links between Germany and Britain did not prevent war in 1914. Some listening to the Japanese prime minister came away with the impression he thinks pecuniary interests may not be strong enough to deter a military clash.
If a conflict between Beijing and Tokyo were to break out, the US could not bank on its other ally in the region, Seoul, given the tense relations between South Korea and Japan which have their own territorial and historical disputes. So Washington would choose between honoring its defense treaty with Japan and avoiding direct conflict with China. As Washington would stand to lose the trust of many allies in the region and is not noted for eating humble pie, the odds would suggest support for Japan. So if there is any parallel with 1914, it could turn out to be in how cascading alliance commitments can cause a wider war.
