The volatile political situation in Europe (and partly in West Asia) led to the Great War 100 years ago, with the Austro-Hungarian Empire and Germany (or the Central Forces) on one side and Britain, France and Russia (or the Allies) on the other. What started essentially as a "European war" soon turned into a world war with the Ottoman Empire and Bulgaria joining the Central Forces and Italy, the United States and Japan joining the Allies.
The international situation today is radically different from what it was 100 years ago. Regional conflicts do exist, but there is no conflict between two major powers or blocs that seems unlikely to be resolved through talks. The main contradictions and conflicts today are the ones between the sole superpower, the US, and emerging powers like China and Russia. Despite the comparative decline in its power, the US is not willing to yield its self-perceived sphere of influence to China or Russia. But despite being uncomfortable with the idea of seeing a powerful China, the US has agreed to establish a "new type of major-power relationship" with China.
China is surrounded by complicated maritime disputes with Japan, Vietnam and the Philippines, but these countries seem to be acting on the instigation of the US, and are not in a position to engage in a large-scale military conflict or war with China. In fact, these countries' attitude toward China depends on the direction Sino-US relations take.
About 120 years ago, Japan launched an aggressive war against China, which ended in the collapse of the Chinese navy and the signing of the unequal Treaty of Shimonoseki, which forced the Qing Dynasty (1644-1911) rulers to cede some of China's territories and pay reparations to Japan. The main reason China suffered such a fiasco was that, as a weakening feudal country, it was not prepared to fight an asymmetrical war with an emerging capitalist power.
China, along with the rest of the world, has undergone considerable changes since then. Today China is the world's second-largest economy and one of the five permanent members of the United Nations Security Council. Despite that - and despite possessing nuclear weapons - China is still a peace-loving nation striving to build a harmonious world.
After being defeated in World War II, Japan has had to follow a pacifist Constitution, written with the help of Allies, mainly the US. And coupled with the economic downturn since the 1980s and the international community's stipulation that allows it to only develop its Self-Defense Forces - as opposed to a full-fledged military - Japan today is in a position that is totally different from the late 19th century.
Yet Japan has taken a dangerous step toward militarization by reinterpreting Article 9 of the Constitution. Since the move allows Japan to dispatch troops overseas to take part in "conflicts", it should be seen as a warning not only to China but also to the international community as a whole.