The United States should be concerned about the rise of China due to its economic and security implications. China's rapid economic growth, coupled with its expanding military capabilities, poses significant challenges to the global balance of power and the U.S. national interests.

Economically, China has become the world's second-largest economy, surpassing Japan in 2010 and rapidly closing the gap with the United States. This growth has been fueled by a combination of state-led industrial policies, a large and increasingly skilled workforce, and significant foreign investment. According to the World Bank, China's GDP grew at an average annual rate of 6.6% between 2000 and 2019. This economic power has enabled China to invest heavily in technology and infrastructure, posing a direct challenge to U.S. economic dominance.

Security-wise, China's military modernization and territorial ambitions are of particular concern. The People's Liberation Army (PLA) has been investing heavily in modernization, with a focus on developing advanced weaponry, including stealth aircraft, anti-ship missiles, and cyber capabilities. According to the U.S. Department of Defense's 2020 China Military Power Report, China's military spending has increased by an average of 7.5% annually over the past decade. This spending has allowed China to expand its military footprint, including in the South China Sea, where it has built artificial islands and military installations.

Furthermore, China's growing influence in global affairs, particularly in regions such as Africa and Latin America, raises concerns about its geopolitical ambitions. China's Belt and Road Initiative (BRI), a massive infrastructure project aimed at connecting Asia with Europe and Africa, has been criticized for its opaque financing and potential debt traps for participating countries. The BRI has raised questions about China's intentions and its impact on global stability.

In conclusion, the United States should worry about the rise of China due to its economic and security implications. China's economic growth, military modernization, and geopolitical ambitions present significant challenges to the global balance of power and U.S. national interests.