As a regular visitor to China, I was surprised earlier this year when I heard for the first time a Chinese official refer to his country as a superpower (chaoji daguo). But China’s view of its place in the international order is changing quickly. In a little-noticed speech last month, before a packed house of China’s senior foreign policy officials and scholars, President Xi Jinping put the world on notice: China has its own ideas about how the world should be run and is prepared, as he put it, to “lead in the reform of global governance.”

Gone is the era of Deng Xiaoping, who called China “a large developing country” and insisted that the country maintain a low profile in foreign policy. These days one seldom even hears officials mention the motto of Mr. Xi’s immediate predecessor, Hu Jintao, who described China as “peacefully rising.” Mr. Xi has made clear that he aims to create a new geostrategic landscape.

His ambition is most evident close to home. Where previous Chinese leaders were content to stake claims based on Chinese sovereignty, he has moved to realize them. Through coercion, co-optation and simple brute force, he is making significant strides toward achieving his declared objective of “unifying China” by 2049, the centenary of the founding of the People’s Republic.

In the South China Sea, Mr. Xi has destabilized the region by developing and militarizing seven artificial features, ignoring the competing claims of five other nations and a 2016 ruling by the Permanent Court of Arbitration at The Hague that rejected China’s claims there. In Hong Kong, Beijing has moved to silence contrarian political voices and has worked to disqualify democracy activists from holding office. China is also placing Taiwan in a political chokehold, pressuring other countries to drop their diplomatic recognition of the island nation and forcing multinational corporations to acknowledge Taiwan as part of China.

But Mr. Xi’s vision of Chinese leadership extends far beyond the country’s own backyard. In 2013 and 2014, he outlined a grand-scale trade and investment plan to revitalize the ancient Silk Road and maritime spice routes, linking China to countries throughout Asia, the Middle East, Europe and Africa. The Belt and Road Initiative, as it is called, has the potential to help meet the $3 trillion annual deficit in global infrastructure spending: Railroads, ports, pipelines and highways built by Chinese workers and funded by Chinese loans are already connecting countries across six global corridors. The plan now includes a digital component (fiber-optic cables, satellite systems and e-commerce) and a “Polar Silk Road” through the Arctic to connect China to Europe more directly.