WASHINGTON -- With preparations for Chinese President Xi Jinping’s September visit to Washington underway, officials in both countries are predictably playing down their differences over China’s outsized territorial claims, backed by the construction of military facilities on previously uninhabited islands and atolls, in the South China Sea. And this diplomatic de-escalation, following months of recriminations and veiled threats, suits Southeast Asian leaders just fine.

Of course, no one in Southeast Asia is ignoring China’s strategic designs. The region’s defense spending has increased by more than 50 percent in the last decade, and some $60 billion has been earmarked for new weapons, especially naval hardware, over the next five years. The white paper on military strategy that China released in May, which touted plans to expand the country’s defense perimeter, intensified neighbors’ concerns, making even more military spending likely. Leaders in the region are now welcoming a stream of U.S. military officials and defense manufacturers to see what America’s Asian “pivot” has to offer.

Beyond new frigates and security guarantees, however, Southeast Asian leaders have refrained from reacting too strongly to China’s offshore ambitions. The economic facts on the ground demand prudence.

In only two decades, China has become Southeast Asian countries’ leading economic partner, boosting its influence throughout the region. Chinese leaders’ constant effort to expand economic cooperation stands in stark contrast to America’s approach to the region.

Consider trade. Since 2000, bilateral trade between China and the 10 members of the Association of Southeast Asian Nations has grown tenfold, from $32 billion to $350 billion last year, and could reach $500 billion in 2015. As China has risen to become Southeast Asia’s largest trading partner, the U.S. has slipped to fourth place, with $206 billion in total trade with ASEAN last year.

Given Southeast Asia’s growing economic importance, the implications of this trend could not be weightier. The ASEAN countries’ combined annual GDP is already $2.4 trillion and growing fast, owing to their rapidly expanding middle class, highly skilled workers, and increasingly upscale markets. If the current trend holds, China’s trade with ASEAN could reach $1 trillion by 2020.

The picture for direct investment -- the financial flows that support the construction of factories, offices, warehouses, mines and farms -- is equally striking. From 1995 to 2003, Chinese companies invested a mere $631 million in ASEAN countries; in 2013, they invested $30 billion. Though China remains well behind Japan, Europe, and the U.S. on this front, it certainly has the potential to catch up, as Chinese private-equity firms increasingly look abroad. Indeed, from agriculture to information technology, the Chinese are diversifying their stakes across the region and embedding their companies in ASEAN’s advanced and frontier economies.

China’s Southeast Asian partners cannot afford to ignore these efforts. That is one reason why all 10 ASEAN countries signed on as founding members of the China-led Asian Infrastructure Investment Bank, despite U.S. opposition. China, which has pledged $100 billion in initial investment, has positioned the AIIB as a rival to the U.S.-dominated World Bank, promising to help Asian countries meet their extensive infrastructure needs.

Clearly, when it comes to its role in Asia, China is thinking big. And there is more. At last year’s Asia-Pacific Economic Cooperation meeting, regional leaders agreed to begin work toward possible adoption of a Chinese-backed free-trade pact -- one that is clearly meant to push back against U.S. President Barack Obama’s Trans-Pacific Partnership, which excludes China.

Whether or not Xi realizes his free-trade ambition, there is no denying China’s commitment to deepening its economic ties in Asia and beyond. The country has pledged some $60 billion to its “One Belt, One Road” initiative, which entails the construction of a Silk Road Economic Belt running through Central Asia, and a Maritime Silk Road connecting China to Southeast Asia, the Indian Ocean, the Middle East and eventually Europe. The U.S., meanwhile, is struggling to cobble together a domestic consensus on trade.

To be sure, China has had its setbacks, too. Canceled railway and hydroelectric projects in Myanmar, and riots in Vietnam over China’s move to drill for oil in disputed waters, reflect the backlash that the country’s resource hunger can generate. But China is also certain to learn from its mistakes, and its leaders have a clear vision of where to place their long-term economic bets.

At a time when partisan divisions are undermining America’s economic leadership, China’s growing influence in Southeast Asia should raise a question: If push comes to shove in the South China Sea, will the U.S. find allies in its corner, or will they just be holding Uncle Sam’s coat?

By Kent Harrington

Kent Harrington, a former senior CIA analyst, has served as National Intelligence officer for East Asia, chief of station in Asia, and the CIA’s director of public affairs.

(Project Syndicate)