With coverage of ISIS and global terrorism dominating the nightly news, ordinary Americans have been inadequately exposed to the rise of another military threat to the United States: China.

While China has challenged the economic dominance of the United States for years, no thanks to Beijing’s effort to devalue the Yuan, it was not until 2015 that the most populous country on earth demonstrated the potential to either lessen American influence in East Asia or attack us directly.

While continued American presence in the region has certainly aggravated China and it’s neighbors, the military threat China poses stems more directly from a long-time territorial dispute in the South China Sea. Since the turn of the twentieth century, China, Taiwan, Malaysia, Vietnam, the Philippines and Brunei have taken turns laying claims to the sea’s mineral rich deposits, as well as ownership over key trade passages, which together generate more than five trillion dollars in annual revenue.

Last year, China’s shift toward a more aggressive approach to the dispute raised a series of red flags for the United States. In an effort to secure the South China Sea and establish a maritime sphere of influence, China began building a series of artificial islands, using them as military bases, complete with fighter jet hangars.

In building these military bases, China violated the Philippines’ Exclusive Economic Zone (EEZ), infringing on Manila’s sovereign rights. Since the United States is a treaty ally of the Philippines, China’s encroachment on Philippine territory can be understood as an indirect attack on U.S. influence in the region.

With this new escalation in militarization, China has additionally lessened the supremacy of the American Seventh Fleet, the preeminent military force in the region, in the eyes of U.S. and Chinese allies alike.

The threat of a direct attack on U.S. forces in the region, however, is also plausible. This summer, the International Court of Justice ruled that most of China’s claims to the South China Sea have no legal basis. Following the decision, anti-American protests, some of which called for war against the United States, broke out in Beijing. While an all-out war with China seems far-fetched, small naval skirmishes most certainly do not.

Thankfully, China has yet to resort to military action. Instead, the nation has rejected the court’s ruling and redoubled its island building efforts, a calculation that resembles the U.S. naval strategy in the nineteenth century.

To counter China’s actions and influence, the United States has implemented Freedom of Navigation operations, sending warships and patrol aircraft since October 2015, as part of a muscle-flexing maneuver in the region.

Nevertheless, China is determined to do whatever it takes to write its own navigation rules in South China Sea, including the setting of “red lines” for neighborhood countries. Recently, China warned Japan to “not send Self-Defense Forces to join U.S. operations that test the freedom of navigation in the disputed South China Sea.”

If not stopped, China may reach its ultimate goal of denying foreign access to the South China Sea altogether, damaging U.S. influence and, potentially, U.S. ships.