The United States had a much stronger economy  and Japan did not have many chances of winning. 

The answer lies in the Second Sino-Japanese war.  It all began ten years ago. China had been in  

relative stagnation for a long time, while Japan  had started its modernization half a century ago  

and had a strong military. This had allowed Japan  to make some expansion. Seeing China in a weak  

state, the Japanese military decided to continue  with enlarging Japan's territory and occupied the  

Chinese province of Manchuria. China did not have  a strong army and could not offer much resistance.  

The Japanese proceeded with expansion and took  over Chinese territories bit by bit. In 1937  

the Japanese seized some Chinese cities. By that  time the Chinese public had become outraged by  

Japanese expansion and demanded resistance. The  Chinese military was too weak to recapture the  

territories. The Chinese decided to capture the  weakly defended Japanese possession in Shanghai.  

Then they could possibly trade it back to Japan  for the return of the territories in the North. 

The Chinese attacked in Shanghai. They  expected to finish the operation quickly,  

but they were unable to overcome the Japanese  defenses. Both sides brought reinforcements and  

the fighting grew larger. Japan wanted to end the  conflict by inflicting a major defeat on China.  

It deployed 200 000 men in North China to go  on offensive and destroy the Chinese forces. 

The Chinese knew of their weakness. They did not  allow themselves to be drawn in a decisive battle  

and offered major resistance  only in the western mountains.  

Japan was unable to destroy the Chinese forces.  But it still could do so in Shanghai. Japan landed  

around 300 000 men in Shanghai and went on a  counterattack. The Chinese made a mistake by  

holding Shanghai for as long as possible and the  Japanese landed another force behind their lines.  

The Chinese were unable to properly react to  the landings and their forces were thrown into  

disarray. Without encountering much resistance the  Japanese now headed towards the Chinese capital  

at Nanjing. The Japanese captured it and a large  part of the city's civilian population perished in  

the following weeks during the Nanjing massacre. Japan had inflicted a major defeat on China  

and now offered peace on harsh terms. Although  the Japanese military had proven to be stronger  

than the Chinese, Japan had other weaknesses.  It was a much smaller country than China and  

had difficulties sustaining a large army. Also  Japan was threatened by other powers and if they  

would move against Japan, It would find itself  in great difficulties. So China expected Japan  

to become weaker as time passed and it decided not  to make peace with Japan for as long as possible. 

Japan could not force China to surrender so it  decided to neutralize it by attacking China's  

economy. The Chinese war industry and its best  agricultural lands were in the central part of the  

country. Japan believed that if it occupied them,  then the Chinese army would become much weaker.  

Then Japan could would not need to sustain a large  force in China and could reduce its garrison. 

The Japanese first wanted to connect their  armies in the North and South of China.  

While most of their armies were reorganizing,  they launched the attack with weaker forces.  

In the South the Chinese brought up reinforcements  and stopped the Japanese on a river line.  

Then they regrouped their units in the North  and deployed a strong force against the Japanese  

northern attack, which halted their offensive. This left a lot of Chinese troops situated  

between the two Japanese armies and Japan set out  to encircle them. The Chinese were ready for that  

and withdrew their forces from the encirclement.  The Japanese then continued to advance west,  

but the Chinese destroyed the dykes on the Yellow  river, which flooded the area between the two  

armies and the Japanese had to stop their advance. The Japanese now set out to capture the lands  

around the Yangtze river and the city of  Wuhan. The floods closed the northern route  

and the Japanese chose to advance along the  Yangtze river. The Chinese had 800 000 men, while  

the Japanese attacking force had only 200 000. The Chinese deployed their troops on the path of  

the Japanese attack and slowed down their advance.  The Japanese then attacked the weak Chinese forces  

in the North and outflanked the Chinese defences.  This helped the Japanese to overcome the Chinese  

on the Yangtze and they now approached Wuhan.  The Chinese abandoned the city to the enemy. 

The Japanese proceeded with securing their  position. They expanded their territory  

to the east and west. Then they set out to  destroy the Chinese armies. They dispersed  

the Chinese forces in the North and returned  to their positions. They then launched an  

attack against the Chinese in the South. Japan had achieved its goal of occupying  

the Chinese war industry. In order to prevent  China circumventing the Japanese strategy by  

bying war materials from overseas,  Japan also occupied China's major ports. 

Japan had deployed 850 000 soldiers to  carry out the conquest and it could now  

start withdrawing them back to Japan to cut down  the expense of the occupation. But the Chinese  

still had formidable forces. They decided  to launch a major counter offensive. 

Its goal was to retake Wuhan and to  achieve smaller gains in several places.  

The offensive was launched in late 1939. But the  Japanese strategy had proven to be effective.  

Without proper equipment the Chinese were  unable to breach the Japanese defences.  

Nevertheless they stopped an attack in South China  and disrupted the Japanese positions near Wuhan. 

The Japanese wanted to restore the security  around Wuhan. They dispersed some Chinese units  

and then extended their territory to the West. The Japanese were able to recover from the  

Chinese offensive, but then the Chinese Communists  launched a series of attacks behind the Japanese  

lines known as the Hundred Regiments Offensive. The Japanese suppressed the offensive and in 1941  

they cleared their occupied areas from most  of the Communist forces and improved their  

defensive positions in North China. In central  China they launched several offensives to weaken  

the Chinese forces. By this time the Chinese  had adapted themselves to Japanese tactics  

and avoided large-scale battles and as a result  the Japanese could not completely destroy them.  

Japan had another problem. China had established  land routes to the ports of the European colonial  

powers and was sourcing war materials from abroad.  After France had been defeated in World War Two,  

Japan occupied the French Indochina  and closed one of the routes. 

Remember that Japan could become  embargoed by the United States?  

Well the United States was opposed to Japanese  expansion. The move into Indochina was the last  

straw and the United States stopped selling oil  to Japan unless it withdrew its forces from China  

and Indochina. Japan got almost all of its oil  from the United States and without a new source,  

its military would become inefficient in a couple  of years. For Japan, withdrawing from China  

was unacceptable. It also realized that, until  the United States controlled its oil supply,  

it could make Japan do whatever it wanted.  So Japan badly needed its own source of oil.  

For this, it could capture the oil fields from the  European colonial powers. This would mean war with  

the United States, a country much more powerful  than Japan, but the risk was considered worth it. 

To answer the question from  the beginning of the video: 

Japan went into war with China, but China  did not surrender. So Japan had to escalate  

the war more and more. Eventually this  caused the United States to embargo Japan  

and the only acceptable way out of this situation  for Japan was attacking the United States. 

Would Japan going to war with America finally  turn the war in China's favor? Well...  

it is a long story. One, which we  hope to tell in a separate video.