Like his predecessors who built the Great Wall to thwart foreign threats, Chinese leader Xi Jinping is raising ramparts to make his nation more self-reliant, a mission has made more imperative.

China has pumped billions of dollars into semiconductor production, stockpiled grains and oil, and established international links to its financial system. At the root of the push is the fear of getting blocked out of Western economies by heavy penalties of the sort the U.S. and European Union have thrust at Russia.