During the confirmation hearing for Pete Hegseth, President-elect Donald Trump’s choice for Secretary of Defense, Sen. Tammy Duckworth asked the nominee for factual details about the Association of Southeast Asian Nations (ASEAN), including its membership and the U.S.’s relationship with member countries.

Hegseth responded that he was unable to name the exact members of ASEAN, yet pointed out U.S. security relationships with South Korea, Japan and Australia—none of which are members of the group in question. (Duckworth suggested Hegseth “do a little homework”)

Still, Duckworth’s question was recognition that Southeast Asia is becoming a key area of geopolitical interest for the U.S., due to its economic dynamism, natural resources, manufacturing strength, and proximity to China, increasingly seen by Washington as the U.S.’s key geopolitical rival. 

So what is ASEAN?

The Association of Southeast Asian Nations, or ASEAN, is an intergovernmental organization that comprises 10 states based in Southeast Asia. Five countries—Thailand, Indonesia, Malaysia, the Philippines, and Singapore—founded the group in 1967. The bloc has since expanded to include Brunei, Vietnam, Laos, Myanmar, and Cambodia. 

The bloc covers a total GDP of around $4.2 trillion and a total population of close to 700 million.

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The group aims to promote cooperation among its members on both economic and security matters. Yet in practice, the group has tended to focus on the former. ASEAN prioritizes consensus among its members, and it has proved difficult to reach agreement on security-related issues like ownership of the South China Sea.

ASEAN member states cover the full range of government types and levels of economic development, such as the oil-rich absolute monarchy of Brunei, the multiparty democracy of the Philippines, and the one-party socialism of Laos. 

Why Southeast Asia matters

Economists believe Southeast Asia is poised to become one of the world’s most dynamic economic regions. A little over 200 million Southeast Asians are youths, which means the region is set to enjoy a growing labor force and consumer pool. 

The International Monetary Fund predicts that Southeast Asia’s GDP will expand by 4.7% this year, compared to 4.5% for China and 2.2% for the U.S. The Asian Development Bank and commercial banks like HSBC and Citigroup also have a positive outlook for the region. 

The region has benefited from the reordering of global supply chains. Countries like Vietnam and Malaysia have gained as companies moved manufacturing out of China.

Southeast Asia also has a significant presence in strategic sectors like chips and green energy. Both Malaysia and Singapore have had a semiconductor industry since the late 1960s; Fortune 500 chipmakers like Intel and Micron have well-established manufacturing in these two countries. 

Indonesia sits on vast reserves of natural resources, including nickel, used to make batteries for electric vehicles.

Why the U.S. cares about Southeast Asia

Southeast Asia has also emerged as a zone of geopolitical interest due to its position between major powers like China, the U.S. and India.

ASEAN professes non-alignment as an organization, yet China is the largest trading partner for many ASEAN economies. Chinese companies see Southeast Asia as a key growth driver, as growth in China slows and as geopolitical tensions threaten to close off access to the U.S. economy. 

Several ASEAN nations also maintain strong defense ties with Washington. The U.S. has a mutual defense treaty with the Philippines, and the U.S. military conducts regular training exercises with Thailand, the Philippines and Singapore. Washington and Hanoi, once former enemies, have also expanded their security relationship, and U.S. navy ships have made port calls in Vietnam in recent years. 

Some Southeast Asian nations are locked in a territorial dispute with China regarding the South China Sea, which houses one of the world’s busiest shipping routes. About one-third of all shipping passes through the region. China, the Philippines, Vietnam, and Malaysia all claim part, if not all, of the South China Sea

The U.S. conducts regular “freedom of navigation” exercises through the South China Sea, and has backed the Philippines in its territorial dispute with China. Yet ASEAN’s policy of consensus has limited its ability to act on the issue, in part due to countries like Cambodia, which leans more towards Beijing.