In first days of July 1937, Chinese and Japanese soldiers skirmished in Wanping, a few miles southwest of what is now the Chinese capital. China’s Chiang Kai-shek then knew his army was no match for Japan’s, and he had many opportunities to avoid battle with a vastly superior foe. Yet he ultimately chose war.

So why did Chiang decide to fight? And how did a minor—and probably accidental—clash turn into years of disastrous conflict? Now, analysts think today’s Asia feels like 1914 Europe, and last month in Davos Japanese Prime Minister Shinzo Abe likened today’s situation involving his country and China to that of England and Germany a hundred years ago. The better comparison, however, is 1937. The parallels between then and now, unfortunately, are striking.

The “China Incident,” as the Japanese then called the war, began on the banks of the Yongding River in Wanping during the night of July 7, 1937. Imperial troops, shooting blanks in an evening exercise, found themselves under fire, presumably from elements of the Chinese 29^th Army. After the minor exchange near Lugouqiao, commonly known as the Marco Polo Bridge, Japanese officers were alarmed when one of their soldiers failed to turn up for a roll call. They then demanded that Chinese guards let them search nearby Wanping, where the Japanese had no general permission to enter.

A refusal triggered days of skirmishes. Once the fighting started, it did not matter that the stray Japanese private, who is thought to have wandered off to urinate, eventually turned up unhurt. Soon, Chiang Kai-shek’s Republic of China was at war. The Japanese in short order would take the Marco Polo Bridge, cut off Beijing from the rest of the country, and seize that city. They would then drive Chiang’s forces from the metropolis of Shanghai, the capital of Nanjing, and most of the rest of eastern China.

Chiang could have avoided the descent into a war in July 1937. In fact, both sides had agreed to a truce after the initial fighting around the Marco Polo Bridge. Yet the agreement did not hold. Oxford professor Rana Mitter compares the events then to those surrounding the assassination of Archduke Franz Ferdinand at Sarajevo in 1914. War, in both cases, was coming.

It is not hard to see why conflict between China and Japan was inevitable in the late 1930s. Japan was obviously determined to control portions of continental Asia. Its troops were stationed near Wanping pursuant to a 1901 treaty signed after foreign powers, including Japan, had put down the Boxer Rebellion. Japan had previously humiliated the Qing dynasty in a quick war ending in 1895, wresting control of Korea and Taiwan. Japan had also grabbed a portion of northeastern China from the Russians in the first decade of the twentieth century and invaded Manchuria in 1931, establishing puppet state of Manchukuo there. The Japanese massacred Chinese under their control.

In the late 1930s there were many incidents involving China’s troops and those of Japan. Most of these were settled quickly because Chinese commanders on the ground would give into Japanese demands or make concessions of some sort. In July 1937, officers guarding Wanping refused Japanese demands and Chiang realized he would have to make a stand. “The dwarf bandits have attacked at Lugouqiao,” he wrote in his diary, using one of his favorite terms for his enemy. “This is the time for the determination to fight.”

Chiang, in other circumstances, might have been willing to give up Beijing, but he had been roundly criticized for letting the Japanese have their way in northeastern China and in any event realized they would not be satisfied with taking only the old imperial capital. As he noted on July 10, “This is the turning point for existence or obliteration.” The decision Chiang made at the Marco Polo Bridge proved to be catastrophic, but at the time the decision to fight was about the only one he could make.

Why is 1937 relevant to us? Today, China, no longer the victim, is aggressive, continually pressing its weaker neighbors to its south and east. For decades, the People’s Republic has been seizing specks in the South China Sea from Vietnam and the Philippines.

Most recently, Chinese vessels took Scarborough Shoal from the Philippines in the middle of 2012. Washington, not wanting to antagonize Beijing and hoping to avoid a confrontation, did nothing to stop Beijing gobbling up the shoal despite America’s mutual defense treaty with Manila. The Chinese were not satisfied with their seizure, however. Now they are pressuring Second Thomas Shoal and other Philippine territory, also in the South China Sea. Beijing claims about 80 percent of that critical body of international water as an internal Chinese lake.

And as soon as the Chinese took Scarborough, they began to increase pressure on the Senkakus in the East China Sea, regularly sending their ships into territorial waters surrounding the islands and sometimes flying planes into airspace there. The barren outcroppings are claimed and in fact administered by Japan, but Beijing, which calls them the Diaoyus, wants them.

Why should the Japanese care about rocks in the East China Sea? The reason is that the Chinese are acting like classic aggressors. They were not satisfied with Scarborough, so they pressured the Senkakus. Chinese analysts, egged on by state media, are now arguing that Beijing should claim Japan’s Okinawa and the rest of the Ryukyu chain.

Chinese leaders, it is true, have not launched a large-scale invasion since 1979. Instead, they now employ “salami-slicing” tactics so as not to invite retaliation. For instance, the Chinese have denied access to Scarborough Shoal with a ring of fishing and patrol vessels so as to effectively control the area. They issued fishing regulations, effective the first of this year, purporting to exercise sovereignty over a large portion of the South China Sea, thereby infringing on freedom of navigation. Moreover, there are indications that Beijing will declare an air-defense identification zone over that sea, just as it did over the East China Sea last November.

The Chinese were not the first to use the salami-slicing stratagem. They were, in fact, victims of these same tactics. As noted, the hardline Japanese military in the 1930s kept advancing in northeastern China, and the Chinese then were continually pushed back and humiliated. By 1937, there was a feeling in Chinese circles that Chiang Kai-shek had no choice but to fight back.

This is, of course, a lesson for Washington today because the parallels between then and now are striking. First, the Japanese military then, like the Chinese one today, was emboldened by success and was ultra-nationalist. The views now expressed by China’s senior officers are deeply troubling. For instance, General Liu Yazhou, the political commissar at the People’s Liberation Army National Defense University, recently urged armed conflict to seize territory. “Those borders where our army has won victories are more peaceful and stable, but those where we were too timid have more disputes,” he said in a recent magazine interview. “An army that fails to achieve victory is nothing.”

Second, the media in the 1930s publicized the idea that Japan was being surrounded by hostile powers that wished to prevent its rise. That’s exactly what the Communist Party says today about China.

Third, then, like now, civilians controlled Asia’s biggest army only loosely. Although many believe that new Chinese ruler Xi Jinping is firmly in command, he appears to be allowing the military to engage in provocative behavior to obtain its support. In the complex bargaining process inside Beijing, Xi may be letting flag officers, head of the most powerful faction in the Party, tell him what policies he will adopt. If the PLA is now Xi Jinping’s faction—as many now believe—it is unlikely that he is in a position to tell the top brass what to do.

Yet whether Xi is an aggressor in his own right—a logical conclusion of the majority view that he is in control of the military—or is being led by the nose by flag officers, China is lashing out, taking on many nations at once. That is the same thing Japan did beginning in the 1930s.

Instead of ignoring Beijing’s provocative behavior, as Washington does, American policymakers should be concerned that countries on China’s periphery, pushed to the limit by Beijing’s unrelenting belligerence, could very well be forced into the same decision that Chiang Kai-shek made in 1937, to resist aggression with force of arms.

World War II, as we now know, started not on the plains of Europe in 1939, but near Beijing two years before, at a village named Wanping.

Gordon G. Chang is the author of The Coming Collapse of China. Follow him on Twitter: @GordonGChang.