Why did the Japanese army enter the northeast of China before September 18th?

1, 1894 After the Sino-Japanese War of 1894, the treaty of shimonoseki was signed, and the Qing government ceded Liaodong Peninsula to Japan.

2. Subsequently, Russia joined forces with France and Germany to force Japan to return the Liaodong Peninsula to the Qing government, which is known as triple interference. 1896, the Qing government was induced to accept the Sino-Russian Secret Treaty, and then demanded the privilege of building the Middle East Railway and its branch lines. /kloc-at the end of 0/897, the Russian fleet broke into Lushunkou, China without authorization; In March of the following year, backed by military pressure, the czar government forcibly "leased" Lushun, Dalian and its adjacent waters to the China government, occupied the entire Liaodong Peninsula, and thus obtained the coveted ice-free port in the Far East. 1900 10 all the strategic locations in the three northeastern provinces are controlled by the Russian army.

3.1During the Russo-Japanese War from February 8, 904 to September 5, 0905, Japan and Russia signed the Portsmouth Treaty, in which Russia in the north and Japan in the south occupied the northeast of China respectively, and allowed Japan to station troops along the Middle East railway.