Modern China sent back before World War II

What happens if modern China and its entire military are sent back to ten years before World War II?

China becomes the strongest immediate military power, but its dependence on modern global food, energy, materials, and technical infrastructure creates a severe survival and sustainment crisis.

In this time-travel scenario, modern China has overwhelming tactical advantages over 1930s forces, including nuclear submarines and generations of advanced equipment. Strategy is harder because the country is a major importer of energy, raw materials, food inputs, and technologies produced through long international chains. Feeding more than a billion people would be the first crisis: contemporary crop yields, irrigation, storage, and multiple global harvest seasons did not yet exist at the required scale. Switching cash crops to food cannot solve the gap quickly because planting seasons, specialized fields, and industrial uses for crops still constrain the decision. China would remain the world's leading military threat, but famine, maintenance, and the need to rebuild precursor technologies could determine whether that power endured.